Frank Lampard said Chelsea need to be more clinical in front of goal after they were made to sweat before securing a 2-1 victory over Watford at Vicarage Road.
The victory was Chelsea's eighth in their past nine matches in all competitions and their fifth on the bounce in the Premier League to move them up to third in the table.
Lampard's decision to put his faith in youth continues to pay dividends with Tammy Abraham, 22, and Christian Pulisic, 21, the scorers against Watford, with Gerard Deulofeu's late VAR-awarded penalty coming too late to stop Chelsea recording a seventh successive away win in all competitions.
They are just two points behind second-placed Manchester City despite being unable to sign players in the summer due to a transfer ban.
But with a trip to City looming and Champions League ties against Ajax and Valencia on the schedule, November will provide much sterner tests of Chelsea's progress than this stroll in the autumn chill at Vicarage Road.
"We played really well, our midfield was outstanding, but we just cannot have that sloppy bit near the end," Lampard said.
"It was a terrible 10 minutes considering how the game had gone. We need to be more clinical, we got a bit sloppy.
"We rely on our goalkeeper for those moments at the end of the game and he did what we needed him to do."
Despite his frustration at Chelsea's nervous finish, Lampard praised their impressive start.
"I'm happy with how the players are playing. It's great to watch," he said.
Chelsea's opener came after only five minutes as Abraham latched on to a pin-point through ball from Jorginho to cooly finish past Ben Foster.
It was Abraham's 10th goal of his breakthrough campaign ending a five-game goal drought for the young England striker, who has scored seven goals in away games this season.
Just as significantly, Jorginho's role in the goal indicated the Italy midfielder's improved form in his second season with Chelsea.
Watford, without a win in the league all season, had Foster to thank for keeping the score to one goal with some superb saves.
The former England goalkeeper kept out Abraham with a fine save, then from Willian's corner, Pulisic looped a header that forced an even better stop by the Watford keeper.
Having won their previous six games on the road in all competitions, Chelsea were in confident mood and Mason Mount was inches away from their second goal when his long-range blast was pushed onto the bar by Foster's fine save.
Foster, 36, denied Mount with another superb stop early in the second half before Pulisic scored what proved to be a decisive second Chelsea goal on 55 minutes.
The United States winger opened his Chelsea account with a hat-trick against Burnley last week and got the final touch on Abraham's low cross to give Chelsea a two-goal cushion.
Pulisic had scored a hat-trick in last weekend's win at Burnley and the United States winger was back on the scoresheet to put the result beyond doubt in the 55th minute.
Watford were given a controversial 80th-minute lifeline when VAR ruled that Jorginho had caught Deulofeu with a trip that drew a theatrical fall from the winger.
Deulofeu dusted himself down to slot home the penalty.
Foster, up for a last second free-kick, almost gave Watford a dramatic point, but his header was brilliantly saved by Kepa Arrizabalaga, who was mobbed by celebrating teammates at the final whistle.
