Mark Wood is a doubt for England's first Ashes Test and is facing a "precautionary scan" on a sore left hamstring.
Wood has been out of action for the past nine months following knee surgery and made his return on day one of the in-house tour match against the England Lions at Perth's Lilac Hill.
The 35-year-old quick bowled eight overs before tea - four in each session - but left the field midway through the afternoon after experiencing discomfort in his second spell.
A spokesperson for the England and Wales Cricket Board said: "The plan for Mark Wood was for him to bowl eight overs today.
"He has some stiffness in his hamstring, which has kept him off the field for some time during the second session of the first day and will undergo a precautionary scan tomorrow.
"He is expected to bowl again in two days' time. It is unlikely he will return to the field today."
Wood has been training with heavy strapping on his leg and while England were optimistic about his recovery, captain Ben Stokes offered what now appear to be prophetic words when asked about the prospect of pairing Wood and Jofra Archer on the eve of the match.
"It's nine days till the first Test starts, that's a lot of time for things to fall into place or for something to happen," he said.
Regardless of the outcome of his check-up, it seems virtually impossible that the tourists would gamble on Wood's fitness when they name their XI at Optus Stadium on November 21.
With a handful of seam options at their disposal and a lack of competitive long-form cricket dating back to August 2024, it would be an enormous risk to throw him into such a big game on the back of this fresh scare.
In better news for England, Stokes announced his readiness for the series with six wickets.
Stokes has not played since July, when he tore a shoulder muscle against India, but proved he is firmly on track for the opening Test by leading the attack.
He took two wickets in each of the first two sessions as he claimed four for 45 in 12 overs, with Josh Tongue the only other bowler to strike as the second string reached 208 for five at tea. He added two more in the final session.
Stokes has been subjected to a stream of barbs from the local media since touching down in Perth but offered a reminder of his threat, dismissing Tom Haines, Jacob Bethell, Jordan Cox and Rehan Ahmed in a pair of robust spells.
Bethell dragged a short ball to square leg having scored just two off 17 balls and looks increasingly unlikely to unseat Ollie Pope from the No3 slot. After a lean white-ball tour of New Zealand, Bethell needed to make a statement to up the pressure on the incumbent and was unable to deliver.
There were runs to be had on an outground offering generous bounce but modest pace, with Durham opener Ben McKinney making 67 before nicking Tongue just after lunch and Cox posting a lively 53.
Cox and Ahmed both shovelled Stokes bouncers to fine-leg as the all-rounder showed his ability to force the breakthroughs that Jofra Archer, Gus Atkinson and Mark Wood were unable to.
England left spinner Shoaib Bashir out of their XI, in a possible nod towards their intentions for the first Test, but he will get the chance to impress when the Lions bowl in the second innings.
