ST KILDA fears the worst for midfielder Luke Dunstan, with the hard-nut Saint expected to require surgery for a shoulder injury suffered against Carlton on Sunday. 

Dunstan, who also underwent shoulder surgery at the end of 2014, came from the field on Sunday in pain and with his left shoulder dislodged, re-emerging later with his arm in a sling. 

Coach Alan Richardson said the popular 21-year-old would undergo scans but the initial diagnosis was not good, souring an impressive 71-point win for the Saints. 

"It's likely he'll have to have surgery," Richardson said. 

Watch Alan Richardson's full media conference 

"That's yet to be confirmed, (but) the early diagnosis is that's what it looks like. 

"It's certainly typical of Luke that he does an injury tackling, because he leads the way for us with his pressure and physicality. 

Half-forward Nathan Wright also suffered a back injury on Sunday, taking a heavy hit to the body just before half time. 

But after his day appeared to be over he returned in the fourth quarter to replace Dunstan and could be fit to face the Sydney Swans next Saturday. 

"If we didn't lose Luke, he (Wright) probably wouldn't have come back on the ground," Richardson said.  

"We needed him to come back on … and he showed a lot of ticker to hang in there for the group and stay out and give us a bit of run when we were one man down. 

"We'll have to wait and see how he pulls up … we'll give him every chance." 

Richardson welcomed the challenge of facing the Swans at Etihad Stadium next Saturday night, with his 10-9 team still a mathematical chance to play finals after North Melbourne lost to the Western Bulldogs on Saturday night.   

The most pleasing aspect for the coach was that his players were showing belief in the game plan and relying less on individual brilliance.  

"In my first couple of years we've relied on 'Rooey' (Nick Riewoldt) to play a really strong role and hit the scoreboard, and we've relied on Jack Steven getting big numbers and playing really penetrating, damaging footy," the coach said. 

"'Rooey' still had a strong game tonight, but for Jack (19 possessions) to get tagged pretty heavily but still play a really selfless game of footy … that was really positive. 

"We've had 17 smothers, so the want for our guys to continue to get after the Blues, even when things were going our way, we're really pleased with that." 

The Saints will need to win their final three matches to play finals for the first time since 2011 and rely on North Melbourne losing its last three. 

St Kilda plays the Swans in round 21 before clashes against Richmond (MCG) and the Brisbane Lions (Etihad Stadium).  

The 12-7 Kangaroos face a testing run home, against Hawthorn (MCG), the Swans (Blundstone Arena) and Greater Western Sydney (Etihad Stadium).