Lawes limped out of Saturday’s Aviva Premiership loss against Leicester and a scan on his knee injury has shown medial ligament damage, according to Northampton head coach Jim Mallinder.
Martin Johnson was already without the suspended Dave Attwood for the Six Nations opener against Wales on 4 February and now it’s Lawes who has been sidelined.
It will mean that Johnson will probably pair Simon Shaw and Tom Palmer for the trip to Cardiff with Louis Deacon in reserve.
“It’s a blow for us and for England,” said Mallinder “He has a medial cruciate ligament problem. He’s gone to see a specialist today but it’s an injury that could take up to 12 weeks. It’s unfortunate, but that’s rugby.
“I’m sure he’ll work hard and get back as soon as he can. He’s a brilliant player, he’s young, he was playing well.
“I’m disappointed for him as well as for the Saints. He’s naturally disappointed but that’s a fact of life and it could be a lot worse – he could have been out for nine months, out for the season and potentially out of the World Cup but, as it is, it’s a short-term problem and a short-term setback.”