Scotland centre Duncan Taylor is a doubt for the World Cup after undergoing extensive knee surgery that has ruled him out of the remainder of the season.

Taylor ruptured his anterior cruciate ligament and posterior cruciate ligament during a second string game for Saracens against Exeter Braves on September 3.

The 29-year-old had surgery on Tuesday and is not expected to be back until June.

If accurate, that estimate for his return would offer little opportunity to prove his fitness in time for Scotland’s Japan 2019 opener against Ireland on September 22.

It is the latest setback for the Scot who was blighted by serious concussion symptoms last season and has also undergone two ankle surgeries and been struck by shoulder and hamstring problems.

“Duncan is out for the season and won’t be back until June,” said Saracens director of Rugby Mark McCall, who in May awarded Taylor a new contract until 2021.

“It’s a huge blow. He’s obviously had a poor year injury-wise. With the head injury he was never sure when he was coming back or when he was going to feel good.

“It’s cruel for one of the most popular players in the squad. It’s just one of those things. We just need to support him as best as we can. I’m optimistic he’ll be back for the World Cup.

“All things going equal he’ll be back in June which gives him time. I’m sure he’ll be in contention.”

Saracens have received more encouraging news from George Kruis, who will make his comeback from ankle surgery against Northampton Saturday.

Kruis was operated on to correct an ongoing issue after Saracens had won the Gallagher Premiership title last season, ruling him out of England’s June tour to South Africa.

Flanker Callum Clark could be involved in the trip to Franklin’s Gardens after recovering from a broken arm, although he is likely to be given one more second string fixture to prove his fitness.

Billy Vunipola’s return from his own fractured arm against Bristol last Saturday was a success and the England number eight will face Saints, potentially as a replacement once again.