Frank Lampard believes the next step for his youthful Chelsea side is to sustain their performance levels across the full 90 minutes of matches.
Chelsea picked up their fifth Premier League win in a row on Saturday with a nervy 2-1 victory against bottom of the table Watford at Vicarage Road.
The Blues looked comfortable after opening up a two-goal lead through Tammy Abraham and Christian Pulisic, only for Gerard Deulofeu to pull one back from the penalty spot 10 minutes from time.
And if not for a last-second save from Kepa Arrizabalaga to deny fellow goalkeeper Ben Foster the home side would have snatched a point, which Lampard admits is an area of concern.
"At times we are certainly producing some of the form that I want from us," he told Chelsea'sofficial website.
"Our work off the ball in some games where we have been pushed hard, like Ajax away and Liverpool, has really pleased me.
"They have worked on that in training to a level where they are fit enough. In periods of games I am pleased with the way we combine and switch the ball. If I've got a gripe it is that we are not sustaining that for long enough at a time."