England and Saracens flyhalf Owen Farrell is in doubt for the rest of season after he was forced to leave the field at half time in the Premiership leaders 28-24 win over second-placed Northampton on Sunday.
Farrell had to be relieved of kicking duties by Argentina's Marcelo Bosch and didn't take the field in the second half at Saracens' home ground in Hendon, north-west London.
England head coach Stuart Lancaster will be hoping that Farrell is fit enough for their end of season tour of New Zealand,
"It's too early to say about Owen. It's a foot injury and you never know with foot injuries," Saracens director of rugby Mark McCall said.
"Owen doesn't remember when it happened," he added. "We'll have news later in the week. He couldn't kick with it."
Saracens eased into an 18-point lead with tries from David Strettle, Kelly Brown and Bosch, but Saints fought back after England's Luther Burrell and Wales' George North both crossed for tries in the final 10 minutes.
Victory meant Saracens now need just two more points to guarantee a home play-off.
"It was tight at the end but I wouldn't want to ignore the first 70 minutes. We were really good and hard to handle at times," McCall said.
"I was chuffed with how we played and I think that's up there with how well we've played all season.
"What I enjoyed was the intent we had in everything we did. Intent to attack, intent carrying, intent at chasing kicks and intent in defence.
"We'll ignore the last 10 minutes because before that we were brilliant."
Second-placed Northampton are 10 points adrift of Saracens and their lead over Leicester, who occupy third, is only three points.
"Saracens dominated the game for 70 minutes. We didn't get many opportunities," said Saints boss Jim Mallinder.
"We're disappointed because the accuracy of our game wasn't quite there, but we showed character to come back.
"We're not playing as well as we did before and during the Six Nations.
"But we're not too concerned because Saracens are a good side and we know we played into their hands a bit."
Mallinder added England hooker Dylan Hartley is expected to return from his shoulder injury before the end of the season, while England and British and Irish Lions prop Alex Corbisiero's comeback from a knee problem is set to be against Bath on May 2.