Ospreys, Wales back row Dan Lydiate a 2018 Six Nations doubt

Dan Lydiate will miss the Six Nations and the rest of the season after undergoing surgery. David Rogers/Getty Images

Warren Gatland has suffered a blow ahead of the 2018 Six Nations, with Wales and Ospreys backrow Dan Lydiate now a doubt for the Championships due to a bicep injury.

The backrow is an area where Wales seem light; Sam Warburton will miss the rest of the season with a neck injury, while Taulupe Faletau is a doubt for the Feb. 3 Six Nations opener against Scotland after suffering a three medial knee ligament injury.

"We'll know a lot more when he has had his scan and the medics can plan the best way forward for him," Ospreys defence coach Brad Davis told the BBC while admitting Lydiate could miss 16 weeks as a worse case scenario.

"Hopefully it is not as serious as it could be. It's absolutely gutting for him because since he's come back he's been a rock in the back row. He gives you that physicality that you need, especially without the ball, so he is definitely going to be a loss for us."