Christian Pulisic and Hakim Ziyech have been ruled out of Chelsea’s game against Liverpool on Sunday along with Ben Chilwell and Thiago Silva.
Timo Werner, who picked up a knock in Monday’s win over Brighton, has been passed fit to play.
Pulisic went off with a hamstring injury during the FA Cup final against Arsenal and recently suffered a setback, while Ziyech picked up a knee injury during the recent pre-season friendly at Brighton.
Chilwell is recovering from an injury he had prior to his move to Chelsea from Leicester and veteran defender Silva is still building up his fitness following his recent arrival at the club.
Lampard said: “Ben Chilwell’s not ready for the game. Christian Pulisic is not ready for the game – similar to Ben, we hope they’ll be training and progressing over the next week or so.
“Ziyech is also not ready for the game. Same story. But Timo Werner’s fit.
“Thiago has been training with us for the last three or four days. We’re just working on his fitness at the moment.”