N'Golo Kante will miss the second leg of Chelsea's Europa League semi-final against Eintracht Frankfurt with a hamstring injury.

Chelsea head coach Maurizio Sarri hopes to have N'Golo Kante back for a potential Europa League final after conceding he made a mistake playing him against Watford.

Kante was forced off with a hamstring injury after just 10 minutes in the 3-0 victory over Watford at Stamford Bridge on Sunday, where second-half goals from Ruben Loftus-Cheek, David Luiz and Gonzalo Higuain proved decisive.

Sarri confessed he should have rested France international Kante after he completed the full 90 minutes in a 1-1 draw away at Eintracht Frankfurt in the first leg of their Europa League semi-final last Thursday.

READ MORE: Chelsea thrash Watford to secure top four spot

Kante will sit out the second leg at Stamford Bridge this Thursday and the Blues' final Premier League outing against Leicester City next Sunday.

However, Sarri suggested the midfielder could be available for the Europa League final in Baku on May 29 should Chelsea advance.

"The problem is with his hamstring. But I think that I made a mistake because, probably, today he had to rest," Sarri told a post-match news conference.

"Sometimes it's very difficult to put on the bench a player so important like [Eden] Hazard, like Kante, but you have to do it. Otherwise you [are taking a] risk, and I have to say that I made a mistake.

"I don't know [how severe the injury is]. We have to wait until tomorrow morning.

"I think it's very difficult to recover him for the next two matches. But we want to play in the final, so he's lucky. We have to try and recover him for the final in case [we get there]."

Chelsea's win sent them third in the Premier League and to the brink of a top-four finish that would guarantee Champions League qualification, though the Europa League offers an alternate route into the continent's premier club competition.

Asked if the Europa League was a luxury for the Blues, Sarri replied: "No, because we want to be in the top four at the end of the Premier League because we want to play in the Champions League.

"We consider the Europa League in a different way; it's a very important competition, we want to win it because we think we deserve to win a trophy this season. So we have two targets."

Watford started well and saw Kepa Arrizabalaga tip Troy Deeney's header onto the post in the first half, but Loftus-Cheek and David Luiz each scored in the space of three second-half minutes to turn the game on its head.

"The result was very, very bad for us. We didn't deserve that bad result," said Watford boss Javi Gracia.

"We had some good moments and performances in the first half, dominating the game and creating chances. We recovered the ball well after losing it, and had a very good, ambitious attitude. But we didn't take the chances.

"We have to be more clinical in that situation, more aggressive in both boxes because in the first half we had the chances.

"The second half we conceded two goals from set-pieces - they always do that one-two at corner kicks, with the quick passes. It's difficult to say I'm happy with the performance because, losing 3-0, I'm not happy."