Yannick Bolasie's late equaliser gave Middlesbrough's fading Championship play-off hopes a boost as Neil Warnock's side held in-form Watford at the Riverside.
The Hornets went ahead through Ismaila Sarr's fortuitous opener as the Senegal forward deflected Philip Zinckernagel's shot from the edge of the box past Marcus Bettinelli.
Duncan Watmore had an equaliser disallowed for offside shortly after half-time, while Joao Pedro twice went close for Watford.
But substitute Bolasie equalised with 12 minutes to go with his side's first effort on target as his diving header from Paddy McNair's wide free-kick beat Daniel Bachmann.
Second-placed Watford dropped points for just the second time in 12 games, but they are still 10 points ahead of third-placed Brentford who have two games in hand.