Watford put the brakes on Chelsea's resurgence by holding the champions to a 0-0 draw at Vicarage Road on Wednesday.
Chelsea, who remain unbeaten since Guus Hiddink took over from Jose Mourinho in December, were unable to find a way through a rock-solid Watford rearguard, with the hosts creating the better opportunities on a night of few chances.
Watford's Odion Ighalo passed up the best opening in the first half when he misjudged the flight of a cross and completely fluffed a header when three metres from goal.
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Diego Costa flashed a first-half shot wide and had a late header superbly saved by Watford keeper Heurelho Gomes, who also reacted quickly to parry an effort from Branislav Ivanovic as Chelsea applied late pressure.
(Reporting by Toby Davis; editing by Ed Osmond)
