SYDNEY captain Josh Kennedy headlines a list of players battling to be fit for Friday night's clash with Geelong at Simonds Stadium.

The Cats have their own worries after youngster Nakia Cockatoo fell victim to his third right hamstring injury of the season, continuing his horror run of soft tissue setbacks. 

Kennedy spent an extended period off the ground in the third term against Hawthorn with a left hamstring issue and will have scans on Monday to find out the severity. 

The 29-year-old, who was playing his 200th game, came back with his thigh heavily strapped and battled through. 

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In other concerns for the Swans, ruckman Sam Naismith received a knock to his already strapped right knee at a centre bounce at the start of the third term against the Hawks. 

The 25-year-old had a spell on the bench and received further treatment for a leg/groin complaint before three-quarter time. 

Fellow big man Callum Sinclair pulled up sore from a marking contest midway through the final term.

The 27-year-old had his left ankle strapped and finished the match, while Jake Lloyd (hip tightness) and Gary Rohan (back spasms) were late withdrawals. 

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For Geelong, Cockatoo re-injured his troublesome right hamstring after bursting away to kick a goal from close range early in the last term against Carlton – his third major – and immediately pulled up short. 

The 20-year-old first injured the same hamstring against the Western Bulldogs in round nine and suffered a repeat of the injury against West Coast in round 13, which kept him out for the last five weeks until his comeback against the Blues. 

Cockatoo has missed a total of six games this season because of right hamstring problems. 

Melbourne has been dealt a serious injury blow, with forward Jesse Hogan having surgery on Sunday to repair the broken collarbone he suffered in a third-quarter bump against North Melbourne. 

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The 22-year-old was crunched by Kangaroos defender Luke McDonald in a contest at ground level and immediately reached for his left arm. 

After an initial assessment on the bench, a visibly sore Hogan went to the rooms supporting his arm and took no further part.

Dees co-captain Nathan Jones (quad) and Bernie Vince (suspension) will be available for selection for Saturday's clash with Greater Western Sydney. 

North Melbourne key forward Jarrad Waite suffered a left calf setback in the third quarter against Melbourne.

The 34-year-old had a compression bandage around his leg and returned to the ground, but was wrapped in cotton wool later in the term after receiving a knock in a marking contest.

Greater Western Sydney midfielder Will Setterfield sat out most of the second half against Fremantle with concussion.

The 19-year-old was tackled to the ground by Docker Lachie Neale and was accidentally kneed in the head by skipper Nat Fyfe, who showed a nice act of sportsmanship by calling for the trainers. 

Setterfield slowly got to his feet and jogged off the field, but did not return after failing a concussion test.

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Gold Coast played the final quarter against Richmond with just one fit player on the bench following injuries to Callum Ah Chee, Alex Sexton and Ben Ainsworth. 

Ah Chee was the first casualty with concussion when he received a heavy bump to his already strapped left shoulder from Tigers defender Dylan Grimes in the second term. 

Sexton was crunched before half-time after courageously going back with the flight of the ball and crashing into a marking contest involving teammate Max Spencer and Tiger Josh Caddy. 

Sexton was slow to get up and was assessed for any possible facial fractures, taking no further part in the match with concussion. 

Ainsworth, meanwhile, injured the medial collateral ligament in his right knee at around the halfway mark of the third quarter and could be out for three weeks. 

The 19-year-old's leg appeared to give way as he slipped to ground while trying to contest an aerial ball. 

Ainsworth was able to jog off the ground for assessment, but was soon icing his leg on the bench. 

Suns ruckman Jarrod Witts (foot) and midfielder Brayden Fiorini (hamstring) were also hampered late in the game.

Fremantle half-back Connor Blakely dislocated his left shoulder twice in the first half against Greater Western Sydney.

The 21-year-old's shoulder first popped out of its socket in the first quarter after he backed into a one-on-one marking contest and slid to the turf.

The medicos were unable to pop it back into place on the bench, so Blakely was accompanied to the rooms with the physio supporting his arm. 

Blakely returned to the ground just before quarter-time with his shoulder heavily strapped, only for it to pop out again midway through the second term when his elbow hit the deck in a tackle. 

The medical team again tried to relocate Blakely's shoulder on the bench without success, so he was taken to the rooms for further care and sat out the game with his arm in a sling. 

Carlton ruckman Matthew Kreuzer was forced to sit out much of the second half against Geelong due to concussion he suffered in a third-quarter tackle from Cats superstar Patrick Dangerfield.

The 28-year-old was wrapped up in a tackle and driven into the ground with his arms pinned, which forced the Blue's head to take the brunt of the impact.

Kreuzer slowly got to his feet and went to the rooms where he failed the routine concussion assessment. 

Hawthorn defender Blake Hardwick sat out two-and-a-half quarters against Sydney with delayed concussion. 

The 20-year-old was tackled strongly by Swans midfielder Isaac Heeney on the boundary line early in the second quarter, but his head did not hit the ground and he continued on.

Hardwick eventually left the ground midway through the term, failing a concussion test and watching the second half from the bench.

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In other injury concerns in round 19:

- Gold Coast midfielder Gary Ablett was a late out against Richmond due to an ongoing hamstring issue. 

- North Melbourne ruckman Braydon Preuss received treatment on his lower back before half-time against Melbourne, but played out the match. 

- Hawthorn midfielder Tom Mitchell sprained his left ankle after being brought to ground in a tackle from Swan Isaac Heeney late in the third quarter. Mitchell had his ankle re-strapped and began the final term on the ground.

- Carlton youngster Zac Fisher experienced a left knee complaint in the second term against Geelong and played the second half with it strapped.

- Melbourne forward Mitch Hannan picked up an elbow sprain against North Melbourne and will be assessed this week. 

- Western Bulldogs defender Lewis Young received treatment in the final term against Essendon for a right knee complaint, but came back on. 

- Essendon midfielder David Myers was assessed for a right hamstring niggle just before three-quarter time against the Western Bulldogs, but he was able to return in the final term.

- Collingwood small forward Jamie Elliott appeared to be favouring an ankle against Adelaide, but played out the match.

- Adelaide second-gamer Alex Keath hurt his wrist in the third quarter against Collingwood and came back after having treatment. 

- Hawthorn captain Jarryd Roughead and midfielder Daniel Howe clashed heads in a friendly fire incident in the opening minute of the match against Sydney. Roughead needed stitches for a gash across his left cheek, while Howe also suffered a cut to his left cheek and had his face taped. The pair returned and got through the match. 

- Hawthorn ruckman Ben McEvoy suffered a bloody nose in a friendly fire knock from teammate Liam Shiels in the second term against Sydney. McEvoy received treatment on the bench and returned with his nose taped. 

- Geelong defender Tom Lonergan received a knee to his lower back/kidney area from Carlton forward Levi Casboult in a third-quarter marking contest. The 33-year-old, who had surgery in 2006 to remove his right kidney, was assessed and played on.