Billy Vunipola is set to miss Saracens’ game against Gloucester this weekend after pulling up in training on Wednesday because of a hamstring issue.

The England player was forced to sit out the rest of the session, three days after he made his return to action following a lengthy absence.

Vunipola played his first game in 15 weeks during a 20-minute cameo at London Irish on Sunday, but the 25-year-old has suffered another setback.

Eddie Jones will name his squad to tour South Africa next week and, with the back-rower struggling to prove his fitness, it puts the number eight’s participation in doubt.

Sarries’ director of rugby Mark McCall is positive about the prognosis, insisting that it is not too serious, but admits he is a huge doubt for their encounter against the Cherry and Whites.

“It is unlikely we would risk him this weekend,” McCall said. “He had some awareness in his hamstring last week but has trained well with us and looked good against London Irish.

“Billy just felt some tightness, but it is not pulled or anything. He was being sensible and it is not in his nature to plough on. We would not play him if we thought that he would pull a hamstring in a game.

“He has looked great in training, looked good against London Irish and trained well with us on Tuesday in a lighter session. The common sense thing to do was pull out of the session which he did.”