Mata's moment of class the difference as United ride luck
Manchester United 1-0 Watford
Juan Mata hauled Manchester United back into the Champions League reckoning with a stunning free-kick to seal victory in a game which should have resulted in Watford's first victory at Old Trafford.
Mata, who was named captain due to the mounting injury crisis at the club, had struggled to make an impact in the game as Odion Ighalo missed a series of chances to win it for Quique Sanchez Flores' team.
But after Anthony Martial had been fouled on the edge of the penalty area by Miguel Britos in the 83rd minute, Mata curled a pinpoint free-kick over the wall and beyond goalkeeper Heurelho Gomes to claim all three points and move United level with Manchester City, who have a game in hand, in fourth place.
And following a season of frustration at Old Trafford, a late surge into the top four could yet extend Louis van Gaal's stay at the club beyond this summer and into the final year of his contract. Despite the thrilling manner of United's 3-2 victory against Arsenal at the weekend, the youth and inexperience of Van Gaal's team were always going to ensure a bump in the road would have to be negotiated at some point.
With Michael Carrick ruled out through injury, 18-year-old defender Timothy Fosu-Mensah was handed his first senior start, alongside Daley Blind at centre-half, to reduce the average age of United's starting 11 to just over 23 years.
The fact that Mata was handed the captaincy by Van Gaal merely underlined the lack of senior figures available. With Wayne Rooney, Chris Smalling, Carrick and Bastian Schweinsteiger all unavailable, Mata was seemingly the only option.
But such has been the unpredictable nature of United's season, nobody could safely predict whether Watford would be brushed aside or if Flores' team would use their experience to send the home side and their promising bunch of kids back to school.
In the first half, at least, Watford held the upper hand, with forwards Troy Deeney and Ighalo repeatedly exposing the weaknesses at the heart of United's defence. They were always going to be a handful for Blind and Fosu-Mensah, and United lived on their wits at times.
Blind did well to intercept a goalbound Ighalo shot after 12 minutes, diverting it behind for a corner, but the Dutch international then dropped his team in it six minutes later by losing possession to the Watford striker, only to see David de Gea save Ighalo's shot. Fosu-Mensah twice produced impressive challenges beyond his years on Ighalo to deny the Nigerian a clean strike at goal, but aside from a dipping volley from Morgan Schneiderlin which bounced just wide on 19 minutes, it was all Watford.
And Ighalo spurned another good chance on 27 minutes, after being fed by Deeney's flick, when he turned Marcos Rojo before seeing his shot run just wide of De Gea's far post.
United, in contrast, were toothless at the other end. Marcus Rashford was starved of service and Memphis Depay spent the opening period shooting high, wide and not-so-handsome.
Martial twice found himself with an opportunity to beat goalkeeper Gomes, but the French forward, who was back in action after missing two games with a tight hamstring, shot tamely at goal. Watford carried all the threat and another mistake by Blind gifted Ighalo another chance - once again wasted - on 42 minutes.
United's injuries were now biting hard, with the lack of creativity on the pitch or options on the bench beginning to tell as Watford maintained their grip in the second half. Mata and Ander Herrera lacked the physical strength to make their quality tell against Watford's imposing midfield and United simply could not get a foothold in the game.
Etienne Capoue gave United an early warning of Watford's ambition by fizzing a 35-yard shot over the crossbar before defender Sebastian Prodl forced a reflex save from De Gea with a flicked header from an inswinging corner. When Ighalo missed another good opportunity on 54 minutes, curling wide after turning Fosu-Mensah, the home crowd began to raise its voice.
In turn, Mata upped his game and Depay attempted to create something out wide. Rashford began to run at the Watford defence, with the youngster's pace at least troubling the visitors' rearguard, but clear-cut chances failed to materialise until Mata hooked a left-foot shot wide from 10 yards on 66 minutes.
Watford continued to put pressure on United, but Nordin Amrabat shot over from six yards before Prodl headed wide at the far post from even closer. United rode their luck all night, but Mata's goal was the one flash of quality and it arrived at a crucial moment.
Independent News Service