Watford's perfect start to season ended with 2-1 defeat by Manchester United
Alexis Sanchez had early effort ruled out for offside
United without England's Luke Shaw and Marcus Rashford
Romelu Lukaku opened scoring with finish from close in
Chris Smalling doubled the lead with superb left-foot volley
Andre Gray gave Watford hope with fierce 65th-minute shot
Nemanja Matic sent off in injury time
Watford at Fulham next; United home to Wolves
Two goals in a devastating three-minute burst from Manchester United set up a 2-1 win over Watford at Vicarage Road, ending the home side's perfect start to the season.
United, who had Nemanja Matic sent off for a second bookable offence in injury time, had an early effort from Alexis Sanchez disallowed for offside but soon took command via a scrappy 35th-minute effort from Romelu Lukaku and a superb left-foot volley from Chris Smalling three minutes later.
Smalling took Marouane Fellaini's knockdown on his chest, swivelled and fired a superb left-foot volley past a bemused Ben Foster, who then saved well from Paul Pogba as United threatened to overrun the home side.
A fierce shot from Andre Gray on 65 minutes, following Abdoulaye Doucoure's cut-back, ignited the second half but United held on with David de Gea saving impressively from Christian Kabasele's header in the final seconds.
Despite the victory, United will be disappointed they allowed Watford back into a match that appeared won when Smalling's goal went in.
"Credit to Watford," said Lukaku. "We were too sloppy but it's another win and we have to keep going. We had to try and score a third but we were sloppy, we have to look again at the images."
United manager Jose Mourinho paid tribute to Lukaku.
"I think this last Romelu Lukaku tackle as a right back shows everything. I think he is the image of the team, a team that played very well in long periods in the first half."