The G-Train close to terminating

St Kilda coach Ross Lyon has indicated that re-drafting Fraser Gehrig in last year's national draft was a mistake as Father Time closes in on the full-forward's AFL career.

Lyon admitted after Friday night's nine-point defeat to Collingwood at Telstra Dome that Gehrig's form was a concern, and gave the impression the 32-year-old might have played his last game for the club.

Gehrig gathered seven disposals and a goal in the match - which Collingwood won 16.7 (103) to 14.10 (94) - and the sum of his five games this season reads: 32 disposals, nine goals and very little pressure on opponents when the Saints are not in possession.

Gehrig retired after last season but was re-drafted by the Saints in November when he wanted to continue his career, but Lyon indicated on Friday night the club had young players waiting in the wings, and that the G-Train had been given his chances.

"Father Time catches up with you. Hindsight's a wonderful thing. He was really keen and trained well over the summer," Lyon said.

"We all respect Fraser and he's been a wonderful contributor to St Kilda and I'll sit down with him during the week.

"But clearly it's an issue. His body's an issue, so it's on the agenda."

Lyon could not fault Gehrig's attitude and work ethic, but said his body was "not what it was", and was satisfied he had given the forward enough chances to prove himself this season.

"I feel like I've given Fraser every opportunity over the last few weeks ... and it's important that's been done, so we'll assess his body and his mind, but ultimately (we have to do) what's best for St Kilda," he said.

Although the Saints were overtaken on the ladder by the Magpies - both sides have 4-4 records - Lyon took several positives from the match, most notably the performance of Luke Ball, who played one of his best games since his struggles with osteitis pubis.

"If you talk about positives to take out of it, he was super," Lyon said.

Collingwood's win was their first over a side in the top eight this season, but coach Mick Malthouse saw too many mistakes to be completely satisfied, although he was impressed by some individual efforts.

Midfielder Dale Thomas and defender Harry O'Brien have struggled this season, but both played crucial roles on Friday night.

Thomas played his best game of the season and booted the goal which put the Magpies in front at halftime, while O'Brien laid a desperate tackle late in the game, which sent Charlie Gardiner's shot at goal for the Saints astray.

"(Thomas) is a highly competitive person by nature and the challenge was thrown out to him and I think he took it and grabbed it ... and O'Brien, I thought Harry was terrific," Malthouse said.