Full-time: Arsenal 1-2 Watford
- Odion Ighalo gives the Hornets the lead.
- Guedioura scores spectacular second goal.
- Danny Welbeck pulls one back for Arsenal.
Full-time: Arsenal 1-2 Watford
Arsenal's hold on the FA Cup is ended in dramatic fashion at the Emirates Stadium. Boos ring out around the Emirates - but what an effort from the Hornets.
Oh, and Welbeck almost grabs another immediately!
Iwobi hits the ball against the post and it bounces back in front of the goal ... the second-half sub, Welbeck, looks certain to score when he spins on the ball in the box, but the ball flashes past the post.
It's wave after wave of Arsenal attack now.
GOAL: Arsenal 1-2 Watford (Welbeck)
Welbeck races onto Ozil's backheel and finds the far corner with his effort. Stand by for a dramatic finish!
Another chance goes begging for the Gunners - and they've been made to pay today.
Alexis charges forward again and pulls back to Chambers, who curls his effort inches wide of the far post.
It's just not been Arsenal's day today.
Gibbs squanders another good chance for the Gunners.
The ball is lifted into the Watford box and Gibbs races on to it at pace, but he can only direct his header directly at the keeper. He should have scored.
Watford have made a couple of changes of their own: Ikechi Anya comes on for Etienne Capoue.
Almen Abdi comes on for Adlene Guedioura, too. Watford are looking to break up the play and waste a bit of time. There's just over ten minutes remaining at the Emirates.
Mesut Ozil goes into the book for a late challenge - the German cuts a frustrated figure on the pitch.
In reality, Arsenal have totally dominated this game, but somehow find themselves trailing 2-0. Arsene Wenger - who is sure to come under pressure if the Gunners lose this - must be seething with what he's witnessed.
Arsene Wenger is rolling the dice now. He has to.
Elmeny, Campell and Giroud replaced by Welbeck, Iwobi and Walcott. Can they lead a dramatic comeback?
GOAL: Arsenal 0-2 Watford (Guedioura)
What. A. Goal.
Adlene Guedioura makes it 2-0 in style, scoring one of the most eye-catching goals you'll see this season.
The ball was laid back to him by Troy Denney and he rocketed it into the top corner.
At the other end though, Costel Pantilimon is called into action, as he saves a firm effort from Girous at his near post.
The game is end-to-end now...
Watford look a threat on the break, particularly through Ighalo, whose pace is causing problems.
He is getting far too much space from the Arsenal centre-backs, mind you.
We've played an hour at the Emirates, meaning Arsenal have 30 minutes to keep their hands on the FA Cup.
Meanwhile, Danny Welbeck is busily warming up on the touchline. He would add a bit more pace and dynamism to the Arsenal forwardline.
How will the cup holders respond? Surely if the scoreline stays like this, the likes of Walcott and Welbeck will be introduced.
Arsene Wenger will be furious with the manner in which they conceded that goal. It was far too easy for Watford.
GOAL: Arsenal 0-1 Watford (Ighalo)
Odion Ighalo has given the Hornets the lead against the run of play. The Arsenal backline are at sixes and sevens, allowing Ighalo to spin in the box and fire into the bottom corner.
In truth, that was Watford's first effort of note on the Arsenal goal.
A reminder of how Arsene Wenger decided to organise his team for this afternoon's game:
Arsenal: Ospina, Chambers, Mertesacker, Gabriel, Gibbs, Coquelin, Elneny, Campbell, Ozil, Alexis, Giroud
Subs: Macey, Bellerin, Monreal, Flamini, Iwobi, Walcott, Welbeck
Right, we're back underway at the Emirates.
Arsenal have dominated the match so far, but have failed to find the right finish in front of goal.
Half-time: Arsenal 0-0 Watford
Ozil has suddenly come to life.
The World Cup-winning star plays the ball through to Joel Campbell, but he cannot keep his effort on target.
From the resulting goal kick, Costel Pantilimon is booked for time-wasting. Huge cheers go around the Emirates for that.
Five minutes to half-time and Watford will be generally pleased with how the match has progressed, even if they haven't posed a threat of their own.
Arsenal and Mohamed Elneny, in particular, cannot afford to keep wasting good chances.
Gabriel needs to watch his step. The Arsenal man is very fired up today, but as he leaps into another challenge, Arsene Wenger must've feared the worst.
Thankfully for the Gunners, he gets the ball on this occasion.
The game has become fragmented in the last few minutes - which must suit Watford.
After that controversial Gabriel tackle, you sense there's a bit of feeling in this one now.
Elneny misses the best chance of the game after the ball falls perfectly for him in the box.
The January signing fires over from great position to the right of goal - that was wild from the new man.
Oh, an interesting incident in the centre of the field. Gabriel and Deeney go for a 50/50 ball, and Deeney is in some trouble.
Gabriel jumped into the tackle and is lucky to stay on the field. That was very naughty of the Arsenal man, who should have been sent off.
Deeney limps away...
Good ball from the right-wing position by Guedioura.
However, Ospina is off his line and just gets to it before Troy Deeney. Watford's best moment of the match so far, that.