Manager Antonio Conte praised the impact of his substitutes as Chelsea again left it late to strike for victory.
The Blues had beaten West Ham on Monday with a late Diego Costa strike, and the Spain international produced the goods three minutes from time against Watford as Conte's side came from behind to win 2-1 at Vicarage Road.
Etienne Capoue fired the hosts ahead 10 minutes into the second half before Conte reacted, introducing Victor Moses, Michy Batshuayi and Cesc Fabregas from the bench, with summer recruit Batshuayi levelling with his first Chelsea goal after Heurelho Gomes failed to deal with an Eden Hazard drive.
And then Fabregas, seemingly down the pecking order under Conte, produced a superb pass into the run of Costa - with the striker coolly stroking home to seal another late win.
Conte is enjoying a perfect start to life at Stamford Bridge and praised the togetherness of his squad after turning to his bench for match-winning inspiration.
Asked about the impact of his replacements, Conte said: "Good impact. But it was the same against West Ham.
"It's normal because you push during the game for 70 minutes, usually the opponents pay for their efforts at the end of the game. When new players come on, there is a great impact.
"I'm pleased for Moses, Cesc and Batshuayi because their impact was very good. It's important for me, this, because it shows a great spirit, the right attitude and commitment.
"When you don't start the game (well), usually you're not happy. The manager must choose the starting XI and then find a solution during the game. In these two games, we saw this.
"I'm pleased for the right commitment, attitude of the players, the right spirit. It's a good family and a good team."
Ever since his unveiling, Conte has stressed the importance of hard work and determination on the training ground as well as in matches, and the former Italy coach feels that extra mile has helped Chelsea deliver two late winners in as many games.
"I think the work always pays off," he added. "We are working very hard and will continue to work very hard. After a bad season like last year, it's not easy to start by winning lots of games and starting in a good way.
"It won't be easy. But I'm pleased because this has happened. We can still improve a lot, but we must continue to work like that."
Watford will be disappointed to have ended the game with nothing to show for their own display having matched Chelsea in a dull first half and taken the lead through a fantastic Capoue strike.
The defeat means Walter Mazzarri is without a win since taking charge, following on from last weekend's 1-1 draw at Southampton.
And the Italian admits he will struggle to sleep after blaming his own side for gifting Chelsea their goals.
"We can hold our heads high," Mazzarri said.
"We are all very proud of the way we played, the staff and the players. We played very well. When you play so well and don't manage to get any points, it leaves you unhappy. So, tonight, I'm not going to sleep very well.
"Like we say in Italy, we complicated our own life. Both goals were from our mistakes. We were not focused at either goal. We have to improve with the ball, keep it better and make use of it. We could have played in a more simple way.
"I'm very disappointed. At the moment, what counts is we have grown as a team and improved compared to last week. We were unlucky."