Watford flood the midfield
Although Conte's side had dominated possession for large periods of the game, Watford arguably deserved their lead after Chelsea failed to provide a cutting edge. Faced with Walter Mazzarri's favoured 3-5-2 formation, the visitors found it difficult to break down a densely populated centre of the pitch.
With central midfielders Oscar, N'Golo Kante and Nemanja Matic receiving very little change from Watford's midfield trio of Valon Behrami, Adlene Guedioura and Etienne Capoue, Chelsea's wide players Pedro and Eden Hazard were forced infield to try and influence the game. Although Branislav Ivanovic and Cesar Azplicueta did try to get forward on occasions, Chelsea often lacked width in their attaching phases.
With three central defenders protecting the same number in front of them for Watford, Chelsea found it difficult to provide any sort of penetration. They were slow and meticulous in their build-up play as lone striker Diego Costa became frustrated, with the Spaniard arguably lucky to stay on the pitch after simulation and a rash challenge.
Chelsea's aging defence looked creaky once more, as a lack of concentration caused them to leave Etienne Capoue free to bury his second goal of the season. Yet going a goal behind arguably played into the hands of the visitors as Conte was forced into a trio of substitutions to chase the game.
Fabregas opens the game up
Victor Moses added pace to the Chelsea set up, whilst the introduction of Michy Batshuayi gave Diego Costa a strike partner and twice as many problems for the Watford defence. With the seemingly out of favour Cesc Fabregas pulling the strings in midfield and running the tempo of the game, his passing ability linking the two powerful and energetic strikers proved too much to handle for a tiring Watford defence.
Batshuayi made an impact within just seven minutes of coming on as he drew Chelsea level, before Fabregas played a world class pass from a deep position to release Costa for Chelsea's second with just three minutes remaining.