Gilbert, 27, suffered a setback in February when he had a screw inserted in the metatarsal bone in his left foot after a training mishap. He recovered in time to take his place in the Saints' line-up for round one, but suffered an injury to the same foot on Saturday and was subbed out of the match.

St Kilda's chief of football, Chris Pelchen, confirmed the injury was a recurrence of the previous issue, but was unable to say on Sunday whether further surgery would be required.

''Sam was checked by club doctors today and requires further assessment on Monday before we can confirm the extent of his injury,'' Pelchen said.

''But he has experienced some recurrence of the foot injury he suffered during the pre-season.''

The initial surgery ruled Gilbert out for six weeks, and any further surgery is likely to sideline him for at least as long.

Coach Alan Richardson admitted the worst-case scenario would be a bitter pill.

''Gilbert has been really good for us, he's played on Jeremy Howe in round one and [Jeremy] Cameron, an All-Australian last week, and he's had one goal kicked on him, so he's been in really good form and he provides really strong leadership for our young guys,'' he said.

''You are always going to miss those players.''

The Saints aren't the only club sweating on the results of scans on a key player, with Brisbane Lions onballer Daniel Rich to find out on Monday whether he has ruptured the anterior cruciate ligament in his right knee.

Rich was taken from the field after a Gold Coast player fell across his legs in the Lions' 53-point loss at Metricon Stadium on Saturday.

Coach Justin Leppitsch said the early outlook on Rich's injury was not optimistic. ''It doesn't look like great news at this point in time,'' he said.

''The doctors weren't overly encouraging with their report. Like all things you have to wait on the scans for this.

''Losing one of your best players … it's a fairly big blow when you talk about your season if it ends up being the case.''

Several other clubs are also licking wounds. A West Coast spokesman confirmed the club was awaiting the outcome of scans on Mark LeCras' right arm after he fell on it awkwardly in the win against St Kilda, but the prognosis wasn't great.

''It could be the same issue he had in the past with his arm,'' coach Adam Simpson said. ''We don't know yet. It doesn't look great, he'll miss weeks.''

A Fremantle spokesman said it was unlikely Garrick Ibbotson would require surgery after he dislocated his right shoulder against Hawthorn on Friday night, but how long he stayed on the sidelines was yet to be determined.