Farrell hurt during Saracens defeat
England suffered an injury scare just over a week before the start of the RBS 6 Nations as Owen Farrell hobbled off in Saracens' 18-6 European Champions Cup defeat to Clermont Auvergne.
Farrell twisted his knee in a tackle with Julien Bardy in the 18th minute of Sunday's contest at the Stade Marcel-Michelin.
The England fly-half received treatment on the pitch before heading down the tunnel for further assessment.
Although Farrell lost his place to George Ford last autumn, Stuart Lancaster will still be hoping the problem is not serious enough to rule the number 10 out of England's Six Nations opener in Wales a week on Friday.
Farrell had missed a penalty before his injury and his replacement Charlie Hodgson also struggled with his kicking as Sarries lost their final Pool One match 18-6.
The defeat was not enough to send Sarries out of the tournament, though. They will travel to Racing Metro in the quarter-finals while group winners Clermont will host Northampton in the last eight.
Clermont took the lead when Farrell gave away a penalty in the seventh minute and his opposite number Camille Lopez converted.
Clermont prop Thomas Domingo was penalised when the scrum collapsed a few minutes later, but Farrell wasted the opportunity to draw level as he dragged his kick left of the posts.
Hodgson spurned another chance to equalise when he sliced a penalty kick wide in the 22nd minute.
Sarries were enjoying the majority of possession, but they did not make their dominance count and Clermont made them pay.
Nine minutes before half-time full-back Nick Abendanon joined the Clermont attack and he powered through the Saracens defence after picking the ball up off scrum-half Morgan Parra. Lopez converted to make it 10-3 at half-time.
Hodgson reduced the deficit to four points with a penalty after the break, but Clermont continued to look the more dangerous of the two teams.
The French team added their second try in the 53rd minute when replacement Vincent Debaty breached the Sarries defence. Lopez failed to convert, skewing his kick right.
Jamie George prevented Clermont from adding to their tally by charging down Brock James' drop-goal attempt in the dying minutes, but the Australian made no mistake from a penalty kick in the 77th minute as the French team strode into the quarter-finals with an impressive win.