Watford stunned FA Cup holders Arsenal with a 2-1 quarter-final victory that piled further pressure on Arsene Wenger at a mutinous Emirates Stadium.
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Recent slip-ups in the Premier League title race and the likelihood that Barcelona will complete a two-legged Champions League victory over Arsenal this week left a third consecutive FA Cup triumph as the most realistic prospect of silverware for long-serving boss Wenger this season.
But they failed to make first-half dominance count, with Mohamed Elneny the main culprit in terms of missed chances, and Watford – without a goal in their previous three matches – capitalised on growing anxiety after the break.
Hornets top scorer Odion Ighalo ended a run of 599 minutes without a goal with an opportunist strike before Adlene Guedioura hit a spectacular second after 63 minutes.
Danny Welbeck reduced the arrears with two minutes to play and fellow substitute Alex Iwobi struck the post in a breathless finale, but Wenger's men could not avoid a first FA Cup defeat since Blackburn Rovers left north London with a shock win in February 2013.
A late equaliser from Anthony Martial saved Manchester United as they preserved their place in the FA Cup with a 1-1 quarter-final draw against West Ham at Old Trafford.
A moment of magic from Dimitri Payet had West Ham seven minutes from a famous victory that would have sent them to a Wembley semi-final, but Martial struck from close range to force a replay.
Playmaker Payet, who has wowed fans throughout his first season in England, had put West Ham in front with an incredible 30-yard free-kick earlier in a second half that also saw both teams have good claims for a penalty turned down.
Martial's intervention means United are still in the FA Cup, a competition that represents their best chance of silverware as they sit behind West Ham in sixth position in the Premier League and are 2-0 down to Liverpool after the first leg of their Europa League last-16 tie.
West Ham, meanwhile, will be still dreaming of the trophy if they can join Crystal Palace, Everton and Watford - who defeated holders Arsenal on Sunday - in the last four.
