Arsenal have gone back into fourth place after edging past Watford, who had captain Troy Deeney sent off 11 minutes into the game
Pierre-Emerick Aubameyang gave Arsenal the lead inside ten minutes after Ben Foster's attempted goal kick came off his leg at close range and ended up in the back of the net
Not long after, Deeney was given his marching orders by referee Craig Pawson after catching Lucas Torreira in the face with an elbow, and despite seeing plenty of chances in an entertaining encounter, Watford were unable to battle back for a point
The result has seen Arsenal keep a clean sheet away from home for the first time this season and puts them back above Chelsea into fourth on goal difference, while the Gunners also have a game in hand over the Blues
Watford began well at Vicarage Road but things soon went downhill as Arsenal took the lead inside ten minutes
 It was a rare mistake from goalkeeper Foster as he dwelled for too long on the ball with Aubameyang baring down on him and as he went to kick it away, the Arsenal striker got a leg in the way to send the ball ricocheting into the back of the net
A minute later and Watford lost their captain Deeney as he was shown a straight red card for an elbow into the face of Torreira
 It took a while for the striker to make his way off the field as he remonstrated with the officials, but the decision was not to be overturned and Deeney will now miss the next three games against Huddersfield, Southampton and Wolves, subject to an appeal
It is sometimes said that teams play better with ten men and this certainly applied to Watford for the remainder of the half
 Craig Cathcart went close in the 20th minute with a close range effort, but was denied by the leg of Bernd Leno
Alex Iwobi did test Foster not long after, but the goalkeeper acrobatically parried the Arsenal forward's effort behind before Leno did the same at the other end to keep out a curling Etienne Capoue free kick
Foster atoned for his first-half mistake early in the second period as he denied Arsenal a second
 It was a strong counter-attack from the visitors, with Iwobi picking out Mkhitaryan at the back post, but his side-footed volley was saved by the outstretched leg of the goalkeeper
 The Arsenal midfielder spurned another glorious chance a few minutes later but powered the ball well wide of the upright
Watford continued to press in an open game and Adam Masina almost equalised in stunning fashion just after the hour mark
 He let fly with a fierce drive from 30 yards out, which pinged off the crossbar before going wide
 With ten minutes to play, Andre Gray then rounded goalkeeper Leno but a sliding challenge from Ainsley Maitland-Niles saw his effort away at the near post
Despite plenty of late pressure from Watford, they were unable to take a deserved point from the  encounter as Arsenal held out for a vital away victory
"I respect the referee's decision, but I don't agree [about Deeney's red card]
 In my opinion it is a yellow card but never a red
 I can't explain what the referee saw to make that decision
"It was an important one
 I prefer to speak about my players who today deserve the recognition
 We don't get points but we had a good performance and we keep playing with the same ambition and desire
""Our position in the table is very important
 It is in our hands, to take the top four
 We were working to push the goalkeeper when he wanted to play like he was playing
 It's a very good action from Auba
"It was Aubameyang's instinct and timing that won the game for Arsenal early on and he was a continuous threat up front - although some of his later finishing can certainly be improved
Speaking to  about his goal, he said: "I was confident, it's a long time that I want to score a goal like this, and tonight it went through, so I was confident, because normally keepers don't know if you're coming back to them, and tonight it was a good goal, for me, I like it
"He is now joint-second in the Premier League top-scorers chart with 18 goals and is on course for a 20-goal haul in his first full season at Arsenal
Watford will travel to already-relegated Huddersfield in the Premier League on Saturday, while it is a big week for Arsenal
 They travel to Napoli in their Europa League quarter-final second leg on Thursday before hosting Crystal Palace in the Premier League on Sunday
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