Ben Earl faces an anxious wait to discover the severity of the knee damage he sustained when warming up for Saracens' 38-10 Gallagher Premiership victory at Harlequins.
Earl suffered the injury shortly before kick-off and a brace was placed on his right leg with the versatile back row, who had been picked on the bench, walking uncomfortably through the assistance of crutches.
England's star of the World Cup will have now the knee scanned, with both Saracens and Red Rose boss Steve Borthwick hoping it is not a significant setback.
"Ben hurt his knee in the warm-up and it's too early for us to know how serious that's going to be. We've lost him probably for a while," said Saracens director of rugby Mark McCall.
Saracens have suffered a succession of injuries in their six matches this season and lost two further players at The Stoop.
Elliot Daly sustained a minor hamstring strain, also in the warm-up, while Alex Lozowski incurred knee damage just seconds into the London derby. They join Callum Hunter-Hill, Nick Isiekwe, Theo McFarland and Earl on the sidelines.
Despite the upheaval to their plans against one of the Premiership's pacesetters this season, they were able to engineer six tries in a win that lifts them to third in the table.
"We had the disruption and we dealt with that really well. It was great experience for Olly Hartley to play with Owen on his inside and Nick Tompkins on his outside. He did outstandingly well," added McCall.
"Tom Parton looked fantastic on the left wing as well. We've picked up a few injuries in the last couple of weeks. People are stepping up and playing out of position. It was a really good win."
Saracens lost their opening two matches but have rebuilt by posting four successive victories.
"We've had three good weeks now. The fundamentals which were poor at the start of the season have got better. Our maul was very effective here and so was our defence," McCall said.
"We've used up to 40 players in four weeks and that allows people to step in when others aren't playing.
"I liked that at the end of the match that when we were 30 points up we were fighting hard to not give away a try and that's a really good side."
Harlequins boss Billy Millard admitted the defeat was a step backwards following last Saturday's victory at Leicester.
"It's disappointing but there's only one option and that's to make this a learning, be really honest with each other and move forward," Millard said.
"We've got a massive game against Northampton next weekend and we've got to get it right. We've been so good so far this season and this is the first time we haven't had that consistent performance for 80 minutes.
"It's a wake up call and sometimes you need this early during the season, but it's definitely a wake up call."
*copy from Press Association.
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