Lawes was forced to pull out of the starting line-up after his knee became swollen following a midweek training session, with Northampton director of rugby Jim Mallinder suggesting he may face up to two weeks on the sidelines.

"He (Lawes) has got a bad knee, he did it a couple of weeks ago and missed the home game against Montpellier with it," said Mallinder, whose son Harry was also forced out of the action after picking up an ankle and knee injury on Friday night.