Sydney star Kieren Jack has been noticeably down on his regular output so far this season and it has now been revealed he has been battling a hip injury.

Jack, who missed the entire JLT Series, returned in round one and has played every game this season, however, coach John Longmire revealed last night he will miss the next fortnight to recover from a hip injury.

“Kieren was one of the players who had a good pre-season but got injured just before he was due to play in the JLT series – with a crook hip – and wasn’t able to get any games under his belt,” Longmire said on Fox Footy's On the Couch.

“We’ve been playing him now for five weeks and it’s not getting better, it’s getting worse, so he needs at least a couple of weeks off.

“Hopefully some rest and recovery over the next few weeks will get him back into good form and get him fit and firing for the rest of the season.”

Jack has averaged just 15.8 disposals, 2.6 tackles and three marks in 2017.