Jack Clifford is a doubt for England's autumn series after dislocating his shoulder in Harlequins' 42-26 Aviva Premiership victory over Sale.
Clifford, 24, departed the bonus-point win at Twickenham Stoop with his right arm in a sling following a collision at the breakdown and is facing a spell on the sidelines with director of rugby John Kingston unable to give a time frame for his return.
Back-row Clifford, who missed the summer tour to Argentina after undergoing surgery on the same joint in April, was playing through the pain barrier due to a chest and arm problem even before damaging his shoulder.
"It look like Jack has dislocated his shoulder. It's frustrating for him. It's too early to say how long he'll be out for," Kingston said.
"To give an insight on where we are injury wise, last night [Thursday] we had a training session here under lights and we actually had five players in doubt.
"Three of them missed and two of them got in and Jack was one of those. He had a sore biceps and pec on the left side, so he had strength tablets to get out on the pitch in the first place.
"It was disappointing because he played ever so well while he was on the pitch."
Injury-ravaged Quins rose to fifth in the Premiership table after Tim Visser crossed twice and were able to celebrate the successful return from injury of England forwards Chris Robshaw and Joe Marler.
"To come away from the games against Leicester and Northampton with just one point, taking into context the challenges we were facing, I didn't think it was fair," Kingston said.
"To get five points against Sale ... I was very pleased for the players. We underperformed in our opening game of the season but since then we've been good without getting the results."
Sale paid the price for a lethargic start but were at least able to claim a bonus point after running in three tries in the final half hour.
"We need to get off the bus with the right mentality because we certainly didn't do that," director of rugby Steve Diamond said.
"I give the lads a lot of leeway in how we prepare for these away games but it didn't work here. We don't need coaches for the players, we need psychologists. It's frustrating.
"Without mentioning any names, one or two of our players didn't have the best games."