From a controversial refereeing call to Watford's super sub, Peter Smith picks out the talking points from Manchester United's defeat at Vicarage Road...
Watford stunned Manchester United 3-1 at Vicarage Road, sending Jose Mourinho's side to their third straight defeat.
After losing the Manchester derby last weekend and then going down to Feyenoord in the Europa League in midweek, United fell behind to Etienne Capoue's opener in the first half on Sunday. Marcus Rashford struck an equaliser after the break but, with United pushing for a winner, substitute Juan Camilo Zuniga scored with his first touch before winning a late penalty for Troy Deeney to wrap up the points.
Here, we look at the talking points from the match.
Mind the gap
Manchester United made an ideal start to the season under Jose Mourinho, winning their first three fixtures. But their defeat to Manchester City at Old Trafford last weekend, followed by this loss at Watford, means United are six points and nine goals worse off than their neighbours, who stormed to another crushing win on Saturday over Bournemouth.
With defending champions Leicester next up, before a trip to Anfield in mid-October, life isn't going to get any easier for Mourinho's men - especially as they also have Europa League commitments around those fixtures.
It's early days but United can ill-afford any more slip-ups or their city rivals could soon be out of sight. Mourinho - who has now tasted defeat in three consecutive games in the same season for the first time since he was at Porto in 2001/02 - needs an instant response.
Foul or no foul on Martial?
Anthony Martial - who had come off worse from a clash of heads with Daryl Janmaat a few minutes earlier - was robbed of possession by Miguel Britos in the build-up to Watford's opener. The Frenchman, who perhaps should have been withdrawn after his collision with Janmaat, had ample time to clear his lines but was caught in possession in United's defensive third.
But did he have claims for a free-kick? Britos appeared to just clip the ball before connecting with Martial's left leg and sending the United man to the floor.Sky Sports pundit Gary Neville felt the referee should have blown his whistle. "It's a foul," he wrote on his Twitter page. "[Britos has] kicked through his left leg to get the ball".
Mourinho agreed. "The referee's and the linesman's mistake is not under my control. I can't do anything to improve it," he said.
Super sub Zuniga
A favourite of Watford boss Walter Mazzarri while he was at Napoli, Juan Camilo Zuniga had played just 18 minutes in the Premier League this season before his sensational substitute appearance against Manchester United.
The Colombia international normally operates as a wing-back but showed the finishing qualities of a striker when he stroked home Watford's second on 83 minutes, just 53 seconds after stepping off the bench.
It was Zuniga's first goal since April 2012, when he netted at Roma for Mazzarri's Napoli. But he wasn't done there. By smartly allowing Isaac Success' pass to roll across him in injury-time, Zuniga drew a clumsy foul from Marouane Fellaini which allowed Deeney to fire in a third from the penalty spot. Not a bad cameo appearance.
Rashford's central claims
Marcus Rashford made his first Premier League start under Jose Mourinho at Vicarage Road but it wasn't until the second half, when the England youngster was moved inside from a wide role on the left, that he made his first true impact on the game.
And what an impact it was, just seconds after his positional shift, Rashford played a one-two with Zlatan Ibrahimovic and, after failing to win an aerial battle in the box, pounced on the loose ball and fired in from close range.
The 62nd-minute goal was United's first shot on target of the game and made Rashford the club's top scorer in 2016 with 10 strikes in all competitions. Remarkably, those goals have come from just 17 shots on target.
It's food for thought for Mourinho, who withdrew Rashford from a lone striker role against Feyenoord after an ineffective hour on Thursday, in which he struggled to link up with team-mates.
The 18-year-old was far more dangerous on Sunday when positioned in the vicinity of Ibrahimovic and Wayne Rooney. Indeed, he made eight of his 18 successful passes in a 14-minute window after stepping inside against Watford.
United's attacking problems
Manchester United managed just two shots on target against Watford and, aside from Rashford's close-range goal and Zlatan Ibrahimovic's second-half header - which drew a superb stop from Heurelho Gomes - the visitors rarely looked like hitting the net.
United created just five chances from open play, according to Opta - the fewest they have made in any Premier League game this season. None of these have been classified as clear-cut openings by the stats company.
Those numbers point to a significant lack of creativity in United's midfield, where Fellaini, Paul Pogba and, further up the pitch, Wayne Rooney struggled on the ball. Rooney's pass completion rate in Watford's half was down to 77.8 per cent, Pogba's just 71.7 per cent.
With pass-masters Ander Herrera and Michael Carrick on the bench, Mourinho was not short on central midfield options. But both players remained in their tracksuits, watching on as United struggled to open up a Watford defence which had been beaten seven times in the previous three Premier League games.