Preview of AFL round 21 matches (all game times are local).

FRIDAY
WESTERN BULLDOGS v GEELONG at Etihad Stadium, 7.40pm
Head to head: Western Bulldogs 54 Geelong 90 Drawn 2

Last time: Geelong 17.14 (116) bt Western Bulldogs 17.12 (114) R9, 2009, Etihad Stadium.

TAB Sportsbet: Western Bulldogs $2.30 Geelong $1.60

Sportingbet: Western Bulldogs $2.28 Geelong $1.65

If Bulldogs captain Brad Johnson had nailed his after-the-siren shot from the forward pocket when the clubs last met, the Dogs would have a top four spot sewn up. As it is, they need to win at least one of this match against the Cats or the following round’s encounter with Collingwood to book a finals double chance. No easy task, particularly given they are missing midfield stars Daniel Cross and Ryan Griffen, key defender Tom Williams and half-forward Daniel Giansiracusa. The Cats have not been the same side in recent times that went unbeaten through the first 13 rounds, with three losses and three wins by less than a kick in the seven rounds since, their only comfortable victory in that time over bottom-placed Melbourne. But with Paul Chapman, Darren Milburn and Max Rooke set to return from injury for this game, they are starting to take on a more familiar formidable look.

Key: Geelong forward Steve Johnson was brilliant with five goals when the sides last met, but has been below par in recent weeks since returning from a hip injury. The Cats need him at his best.

Tip: Geelong by 4 points
SATURDAY
CARLTON v MELBOURNE at Etihad Stadium, 2.10pm
Head to head: Carlton 110 Melbourne 88 Drawn 2

Last time: Carlton 15.11 (101) bt Melbourne 9.14 (68) R5, 2008, MCG.

TAB Sportsbet: Carlton $1.07 Melbourne $8.00

Sportingbet: Carlton $1.08 Melbourne $8.00

The Blues have already booked their first finals berth since 2001, and are in some hot form, having burnt off Geelong at the MCG and then Port Adelaide at AAMI Stadium with powerful finishes to games in the past two rounds. They still hold some hope of sneaking into the top four if the Bulldogs slip up over the remaining two rounds and they can beat Melbourne and Adelaide. The first leg of that double, beating the Demons, should not pose too many problems. While Melbourne showed some good signs in thrashing Fremantle last round, Carlton are a much classier side and have much more to play for. The Demons also stand to lose significant ground at the national draft if they notch another win.

Key: Blues spearhead Brendan Fevola snared seven goals from as many kicks when these sides last met. He currently leads the AFL goal-kicking tally by three and if the Carlton midfield’s good form continues he could set himself up for his second Coleman Medal.

Tip: Carlton by 40 points
ADELAIDE v WEST COAST at AAMI Stadium, 2.40pm
Head to head: Adelaide 14 West Coast 18 Drawn 0

Last time: West Coast 14.13 (97) bt Adelaide 5.17 (47) R9, 2008, Subiaco.

TAB Sportsbet: Adelaide $1.14 West Coast $5.50

Sportingbet: Adelaide $1.17 West Coast $5.00

After barren times since Chris Judd and Ben Cousins left at the end of 2007, the Eagles are finally showing some signs of life, with three wins in a row. Most impressive was their defeat of the Bulldogs at Etihad Stadium in round 19, their first win outside of Perth since 2007. They will be keen to keep the momentum going and will draw some confidence from their 50-point win over the Crows in their last meeting. But that was at Subiaco and came more than a year ago. While Adelaide have lost three of their past five games, those defeats have come against the competition’s top three sides – St Kilda, Geelong and Collingwood. The Crows have shown remarkable consistency in beating the sides they are expected to and as one of the clubs still in the running for a top four berth are unlikely to let this one slip.

Key: The Crows would have been extremely encouraged by the strong return of injury-prone key forward Trent Hentschel against Hawthorn last weekend, his first match since round two and will be hoping with matches under his belt he only gets better.

Tip: Adelaide by 30 points
BRISBANE v PORT ADELAIDE at the Gabba, 7.10pm
Head to head: Brisbane 10 Port Adelaide 11 Drawn 2

Last time: Port Adelaide 19.14 (128) bt Brisbane 11.14 (80) R14, 2009, AAMI Stadium.

TAB Sportsbet: Brisbane $1.14 Port Adelaide $5.50

Sportingbet: Brisbane $1.17 Port Adelaide $5.00

This clash comes just seven weeks after these clubs’ last meeting and it is not only that quirk of scheduling that has the recent encounter still very fresh in the Lions’ minds. Brisbane players have freely admitted they allowed their Power opponents to bully them and get under their skin on that occasion, with the normally cool Jared Brennan so irked by Josh Carr he headbutted him and earned himself a suspension. Port took advantage of Brisbane’s rattled state to outscore them 6.8 to 0.3 in the last quarter and comfortably win what had been a tight contest. The Lions will be out to turn the tables both in the physical stakes and on the scoreboard. But the Power have no shortage of motivation either, with their finals hopes fast slipping away after tame losses to Fremantle and Carlton in the past two rounds and a desperate need to show some backbone.

Key: The Power have skill and pace, but need to produce a consistent team effort across four quarters if they are to shake their reputation for unreliability and revive their top eight chances.

Tip: Brisbane by 18 points
RICHMOND v HAWTHORN at the MCG, 7.10pm
Head to head: Richmond 82 Hawthorn 64 Drawn 0

Last time: Richmond 16.9 (105) bt Hawthorn 10.16 (76) R20, 2008, MCG.

TAB Sportsbet: Richmond $3.10 Hawthorn $1.35

Sportingbet: Richmond $3.20 Hawthorn $1.35

The Hawks still hold slim hopes of making the finals and keeping their premiership defence alive, but after losing seven of their past nine games it would be a hollow achievement if they snuck in to the eight through the failure of higher-placed teams to finish the deal. While they showed a few bursts of decent football against the Crows last round, for the most part they lacked fluidity or firepower. Even so, they should be good enough to down a Richmond side that is performing dismally. After showing a few heartening signs under caretaker coach Jade Rawlings, the Tigers have gone downhill fast in the past two rounds. Their round 19 loss to Sydney prompted Rawlings to publicly highlight a culture of players disappearing under pressure. Their response was an even less competitive effort against Collingwood last round, with the only spark they showed in the one-sided contest coming in off-the-ball scuffles.

Key: While hard-nosed midfielders Sam Mitchell and Jordan Lewis continue to win the ball, the Hawks need to find more run than they have managed in recent weeks if they are to break their losing streak.

Tip: Hawthorn by 20 points
SUNDAY
ST KILDA v NORTH MELBOURNE at Etihad Stadium, 1.10pm
Head to head: St Kilda 72 North Melbourne 70 Drawn 2

Last time: St Kilda 15.13 (103) bt North Melbourne 9.3 (57) R11, 2009, Etihad Stadium.

TAB Sportsbet: St Kilda $1.05 North Melbourne $9.00

Sportingbet: St Kilda $1.05 North Melbourne $10.00

The Saints are in unfamiliar territory, coming off their first loss of the season against Essendon last round. Unfortunately, it is a feeling that has become all too familiar to North Melbourne, who have managed just one win and a draw in the past 11 rounds. With finals just around the corner, St Kilda will have been stung into action by their loss to the Bombers and keen to prove they have not lost the aura they developed through the first 19 rounds. Most significantly, the Bombers were the first opponent to top the 100-point mark against them all season and managed to do it by three-quarter time. Expect St Kilda to come out with all of the tackling ferocity and defensive pressure that they had previously made their hallmark. They will also be desperate to win a lot more of the contested ball than they did against the Bombers.

Key: North’s timing could not have been worse – as daunting as it has been for most clubs coming up against the Saints this season, no one has yet had to face them on the rebound.

Tip: St Kilda by 55 points
COLLINGWOOD v SYDNEY at the MCG, 2.10pm
Head to head: Collingwood 134 Sydney 79 Drawn 1

Last time: Collingwood 11.13 (89) bt Sydney 9.12 (66) R12, 2009, ANZ Stadium.

TAB Sportsbet: Collingwood $1.18 Sydney $4.65

Sportingbet: Collingwood $1.20 Sydney $4.50

Collingwood have had a hold on Sydney in recent years, winning their past seven encounters in a record that stretches back to 2006. That is despite the Swans spending most of that time either above the Magpies on the ladder or around the same mark. So, on face value, that could spell trouble for Sydney, given Collingwood are now firmly entrenched in the top four – after winning 11 of their past 12 games – while the Swans are expected to miss the finals for the first time in seven years. But while Sydney are entering a difficult transition phase – with Leo Barry and Jared Crouch having added their names to a list of retirees already including Barry Hall and Michael O’Loughlin – they have shown in recent weeks they will not fade without a fight. They have pushed the top two sides hard in the past three rounds, going down by a point to St Kilda and five points to Geelong. Even if their glory era is ending, a win over Collingwood at the MCG would be sweet.

Key: Not even roughhouse tactics from Richmond last weekend could stop Collingwood magician Alan Didak continuing career-best form. He was best afield last time against the Swans and they need to find a way to prevent a repeat performance.

Tip: Collingwood by 15 points
FREMANTLE v ESSENDON at Subiaco, 2.40pm
Head to head: Fremantle 6 Essendon 16 Drawn 0

Last time: Essendon 16.13 (109) bt Fremantle 10.11 (71) R2, 2009, Etihad Stadium.

TAB Sportsbet: Fremantle $1.85 Essendon $1.90

Sportingbet: Fremantle $1.87 Essendon $1.95

Essendon will be on an enormous high after their stunning upset of previously unbeaten St Kilda, which lifted them into eighth spot. But the surge of confidence that victory sparked will have been tempered by injuries to ruckman Patrick Ryder, running defender Courtenay Dempsey and veteran key backman Dustin Fletcher. The Bombers were wonderful against the Saints and solid in drawing with Brisbane the round before that. But it should be remembered that a round earlier they suffered a surprise loss to West Coast at Subiaco, so they will be a little wary about this trip back to Perth. It is also worth noting that while the Dockers put in a shocker against Melbourne at the MCG last weekend, they are no easybeats at home, where they have won their past two matches – against West Coast and Port Adelaide. The towering presence of Fremantle ruckman Aaron Sandilands will also a worry a weakened Bombers ruck contingent.

Key: The Bombers need to avoid an emotional letdown after their biggest win of the year. The Subiaco surface should suit their running game, but to get that going they need to reproduce similar intensity to that which helped them win the ball against the Saints.

Tip: Essendon by 20 points