Australia's depleted batting stocks have been further devastated with Usman Khawaja in serious doubt for the start of the home summer after tearing the meniscus in his left knee.
Khawaja failed to take the field on day three of the second Test against Pakistan in Abu Dhabi after twisting his left knee awkwardly during a throwing drill in the warm-up.
The opening batsman, who was man of the match during the drawn first Test in Dubai, tore his anterior cruciate ligament in the same knee in 2014.
Scans have confirmed Khawaja has avoided further damage to his ACL graft but suffered a meniscal tear which is likely to require surgery.
Depending on the severity of the tear, the injury could sideline Khawaja for up to six weeks.
At the very least, Khawaja faces an uphill battle to be available when Australia host India in the first of four Tests at Adelaide Oval starting December 6.
The Queenslander will see a knee surgeon upon returning to Australia to consider his options.
Khawaja appears highly unlikely to bat when Australia resume at 1-47 on Friday, requiring another 491 runs to pull off a world-record run chase in the series-decider.
A team spokesman said Khawaja's function and pain levels would be monitored during the day but the 31-year-old was limping heavily when the team arrived at Sheikh Zayed Stadium.
Even if Khawaja does bat, the time he spent off the field prevents him from coming in higher than No.7 during the first two hours of the innings.
Veteran paceman Peter Siddle said Khawaja appeared to have hurt himself in innocuous circumstances.
"It was just something in warm-up. We were throwing the ball," Siddle said after play on Thursday.
"I don't know what specifically happened. It's disappointing for him."
Australia can ill-afford to lose Khawaja, who has become the most senior batsman in a heavily-depleted top six following the suspensions handed to Steve Smith and David Warner.
The injury is shocking timing for the left-hander, who defied his doubters to post scores of 141 and 85 and spearhead Australia's remarkable comeback in Dubai.
"He was initially very flat, knowing that he can't get out there with the boys and help out," Siddle said.
"But I think throughout the day he was up and about, moving around, helping us when we came in and trying to help us in the rooms. He's a positive guy, so fingers crossed for him."
Aaron Finch (24 not out) and Travis Head (17 not out) will resume on Friday with Australia needing a miracle to avoid a crushing defeat.
No Test side in history has ever successfully chased a fourth-innings target greater than 418.