The defending Premier League champions have won three of their last seven games in all competitions to leave their title challenge in doubt.
Chelsea have already lost to Burnley and Crystal Palace in the 2017-18 season so far, while the Blues suffered a 1-0 defeat at the hands of Premier League leaders Manchester City.
The title holders won their opening two Champions League fixtures before a 3-3 loss to Serie A holders AS Roma at Stamford Bridge last month.
Chelsea suffered a 3-0 loss to the Italian giants in Rome on Tuesday night as Antonio Conte’s slipped to second place in Group B.
The defending Premier League champions won’t have much time to dwell on their disappointing loss ahead of the visit of Manchester United this weekend.
Former Chelsea midfielder Lampard believes the Blues are still adjusting to the departures of Diego Costa and Nemanja Matic.
“The signings in the summer was an issue,” Lampard told BT Sport.
“Losing Costa, we knew it was coming. Morata was a good signing. Matic was a big loss for Chelsea to take. Whether they’ve gone on and made strides from last year.
“He hasn’t becoming a bad manager over night. When you start losing games if you don’t have consistency in your starting XI, things change.”
Chelsea won the Premier League title with two games to spare after finishing seven points ahead of Tottenham Hotspur last term.
The Blues signed six players in the summer transfer window to bolster their squad ahead of a return to the Champions League.
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