Liam Henry's move across the Nullarbor could not have started out better for most of his first two appearances in St Kilda colours.

The former Fremantle talent was arguably his new club's best performer in its loss to Geelong and one of the driving reasons for their win over Collingwood.

That was until something did not feel right at the back of his left hamstring in the final minutes of the game.

Coach Ross Lyon walked into his press conference after the Saints' 15-point victory on Thursday night, willing, pushing and hoping that Henry's slight hobble was more tightness.

"We're concerned about him, but in the end, it might be just severe cramp," Lyon said less than half an hour of last seeing Henry in the changerooms after the final siren.

"I think that because we all acknowledge his speed and his run."

Little did Lyon know the extent of the strain that fortunately was not a full tear.

It was, as far as strained hamstrings go, the worst possible scenario.

The club's medicos ruled the pacy wingman turn onballer out for up to eight weeks.

Six weeks at best was the most hopeful diagnosis after conservative assessments are commonplace because of the nature of tendon tissues in leg muscles not having much blood flow to recover quicker.

Even youngsters like the 22-year-old Henry don't come back earlier than they're told.

The Noongar/Wajuk and Walmadjari man was assessed with a high-grade hamstring strain after scans were conducted days later.

"This is obviously a terrible blow for Liam, who has impressed in his first two games at the club," St Kilda general manager of football David Misson said.

"Liam's setback is far greater than we initially thought, especially given he has never had an injury of this type before.

"At this stage, Liam's return-to-play timeline sits at approximately six to eight weeks.

"The shorter turnaround between games early in the year has presented challenges, however, we have full confidence that Liam will attack his rehab with the same intensity he does on game day to make himself available as soon as possible."

Henry had been pretty optimistic moments after the encounter at the MCG.

He told Triple M radio the hamstring still felt "pretty good".

"I think we'll reassess it (on Friday) a bit when we get a scan. Hopefully it's just a little (strain)," he said.

"I'm a bit emotional about it, but hopefully I will get back on the horse, get it right and be back with the boys."

Henry added that the move to St Kilda to link up with Lyon, Henry's coach during his debut season at the Dockers back in 2019, had been sensational until the injury.

"Ross always goes on about confidence comes about from actions," he said.

"So I had a really good preseason after I did like 98 per cent of that, and all my actions comes from that and all the stuff I do during the week for the game.

"It's definitely what I play off for my confidence.

"I'm playing a new role this year and I like the fact I can play off instinct a bit. That's really helped me to be more confident in my ability."

Henry revealed his admiration, for UFC legend Conor McGregor following the themed Spud's Game – named after former St Kilda champion and mental health advocate, Danny Frawley.

The former Christ Church Grammar School student in Perth after growing up in bush towns, Tammin and Fitzroy Crossing in rural Western Australia, in-between living in Port Lincoln in South Australia, says he tends to stick to the philosophies from the Irish fighting legend ahead of going out and performing to keep this head clear.

Everything he does from the preparation allows (Conor) to be free in the octagon and that's what I want to be free on the footy field," Henry said.

"When I cross the white line, I just want it to be me, the footy and the goals because I want to play on instinct."