Hawthorn speedster Isaac Smith could join Sydney co-captain Kieren Jack in sitting out most of the AFL finals series.

The pair suffered knee injuries on Saturday and the Swans have announced that Jack will miss three weeks with damage to his left medial ligament.

That means the only way Jack plays again this season is if Sydney makes the grand final.

Smith limped off the MCG after being brought down in a tackle against Carlton and there is strong speculation he also has a medial ligament injury.

There appears little chance that the Hawks speedster will be ready for Friday night’s qualifying final against West Coast in Perth.

Smith’s absence would be a significant blow for Hawthorn, given the importance of foot speed at Domain Stadium.

But one of the positives for Hawthorn out of the win over Carlton was the continued return to form by Bradley Hill, another of their fastest ball carriers.

While the Hawks remain the premiership favourites, Smith’s injury is another chink in their armour.

They have also suffered upset losses to Richmond and Port Adelaide in the last six matches.

Captain Luke Hodge owes the club after he was caught drink-driving last Thursday night.

The Hawks star was already serving a two-game AFL suspension.

But a significant plus for Hawthorn has been their round-19 win over the Eagles, also in Perth.

“Not too many sides go over there and win, so the fact we’ve done it in the last six weeks is pretty handy,” said Hawks coach Alastair Clarkson.

“They’re not absolutely invincible on that oval, (but) we’re going to have to play at our very, very best to get the job done.”

Smith and Jack are among several finals-bound players who have injury concerns.

West Coast midfielder Chris Masten is unlikely to play against Hawthorn because of a hamstring injury.

But Adelaide Brodie Smith (ankle) and Western Bulldogs forward Stewart Crameri (hip and knee) should be available for next Saturday’s elimination final at the MCG.