Rugby World Cup 2015: Wales' Jonathan Davies rues knee injury

Jonathan Davies joined French side Clermont Auvergne from Scarlets in 2014

Wales centre Jonathan Davies says he had to "use his head, not his heart" as a knee injury ruled him out of the World Cup.

Davies, 27, ruptured his anterior cruciate ligament (ACL) playing for his French club Clermont Auvergne.

He could be out for up to seven months and did not want to risk worsening the injury at the World Cup.

"I've done an ACL before so I know what's coming and it's going to be tough," Davies told BBC Wales Sport.

"But sometimes you've got to use your head, not your heart.

"I didn't want to be going into a major tournament like that, knowing that there's something not right with my knee. It's not ideal but it could be worse."

British and Irish Lion Davies has been first choice in Wales' midfield alongside Jamie Roberts.

His injury could now present an opportunity for his former Scarlets team-mate Scott Williams, who pushed the pair for a starting place during the 2015 Six Nations.

Jonathan Davies (left) and Scott Williams were midfield partners for Scarlets before Davies joined Clermont

In Davies' absence, the centres named in Wales' World Cup training squad were Roberts, Williams and young Newport Gwent Dragons pair Tyler Morgan and Jack Dixon.

The other midfield options in Warren Gatland's 47-man party are Northampton wing George North and Gloucester utility back James Hook.

Having played for Wales at the 2011 World Cup in New Zealand, Davies is frustrated to be missing out on this year's tournament.

"The World Cup squad was announced on Monday and you feel a bit disappointed not being involved," he added.

"Once the games start coming around, then it might sink in.

"Scott [Williams] has been involved with the squad and done exceptionally well when he's had opportunities.

"A lot of people are saying he's the obvious choice and I would pick him as well. He's got a lot to offer the team."