The No8 was central to Saracens’ success in winning the European Champions Cup and Premiership last term and is set to resume club duties when they face Bath in the Premiership on Sunday, a week before the Cup quarter-final against Glasgow Warriors at Allianz Park.
Vunipola returned from knee surgery three weeks earlier than expected to feature in the past two championship games, making his first Test start since November in the 13-9 loss to Ireland on Saturday. The powerful forward is a favourite to make the Lions tour to New Zealand in the summer but believes he has to significantly improved his fitness to make that happen and also help the club to more success.
Vunipola said: “I believe I need to get fitter. I felt good out there, but it’s amazing how much running you can do, how much training you can do, but nothing will ever compare to a full Test match, so I just need to get back on the pitch and get some game time.
“I have just got to go back to the club and see where we can get to in Europe and the Premiership.”
Lions coach Warren Gatland will name his tour party on April 19 and by then Vunipola hopes to have returned to the form that made him the most dangerous No8 in world rugby last season.
He is also determined to help England bounce back from their loss to Ireland, a result that stopped Eddie Jones’s side setting a world record for consecutive victories.
“Hopefully, we can do better and I have every confidence in the England coaching staff,” said Vunipola.
“I just want to keep it very, very professional, take it one step at a time. If you look at the best team in the world and how they react to a loss, they always come back bigger and better, and that’s the focus for us.”
Ireland fly-half Johnny Sexton took a number of heavy hits from England players and left the ground with his left arm in a sling.
England lock Joe Launchbury denied they tried to rough him up but admitted: “Sexton makes them tick in attack. It doesn’t take a rugby genius to work out how involved he is in their attack, how many times he gets his hands on the ball and we wanted to disrupt that rhythm... I don’t think any of the collisions were particularly late.”