Mateo Kovacic could miss Chelsea's next two games with an Achilles injury sustained against West Ham, Frank Lampard has revealed. 

Croatia international Kovacic went off in the 53rd minute of Chelsea's 3-2 loss to struggling West Ham at London Stadium on Wednesday. 

The defeat was a blow to Chelsea's hopes of securing Champions League qualification and Lampard confirmed they will be without Kovacic when they attempt to get back on track against Watford at Stamford Bridge on Saturday. 

Fikayo Tomori will also be absent as he continues to recover from a muscle injury. 

"Fikayo is still not fit. He's hopefully going be training with us somewhere through next week," said Lampard. 

"He's doing a lot of work, it's just the last bit to get him on the training pitch that's been a bit tough. 

"Kovacic is going to be out, he hurt his Achilles during the West Ham game and will miss this one and possibly the one after that. Hopefully it won't be too long after that." 

Marcos Alonso was heavily criticised by Sky Sports pundit Gary Neville during the coverage of the game for failing to track back for Andriy Yarmolenko's 89th-minute winner. 

While Lampard accepted the left-back could have done more, he has not spoken to Alonso about the incident. 

"It's not important with isolated 'slatings' – it's much easier to comment from afar," said Lampard. 

"We do try to play football, we're trying to be progressive but we don't want to concede. Recovery runs are a huge part of football and the players must do them whether it's the first or 90th minute. 

"I don't think it's quite fair to just look at Marcos. In that isolated incident yes, he can recover better and we can recover better as a team. 

"But that has to be fundamental to the team. You have to run backwards as much as you run fast forwards and you have to have that desire to make difficult runs to help the team. I can't complain about the team about that this year. 

"When you isolate one goal that's so crucial because it wins the points, fair enough. But I know with my players that generally we have a desire to press very well off the ball and when it goes beyond us to recover and get there. 

"It was a game where we slipped up, and it's not just that mistake, there were other mistakes, and we lost the game for it." 

He added: "I haven't spoken to him about it. I think it's a dangerous game to comment on every pundit, because you'd probably have to talk to all your players every week and that's the nature of the beast. 

"If I felt a player needed help or support in those situations I would do. We as players and myself in my job are probably the biggest self-critics, we analyse games, we go over them and talk to the players individual and collectively, and that's my main focus, not so much what comes from outside."