Holders Arsenal were dumped out of the FA Cup by Watford on Sunday, while Anthony Martial's 83rd-minute goal earned Manchester United a 1-1 draw with West Ham United. Odion Ighalo and Adlene Guedioura ended Arsenal's two-year reign as FA Cup holders as Watford won 2-1 at the Emirates Stadium to join Crystal Palace and Everton in the semi-finals.
Manchester United looked set to follow Arsenal out of the competition after Dimitri Payet put West Ham ahead with a stunning free-kick at Old Trafford, but French forward Martial spared manager Louis van Gaal from another wave of unflattering headlines with a late volleyed equaliser.
"Our fantastic run has come to an end on a day where we felt that our performance deserved a win," said Arsenal manager Arsene Wenger, whose side replied through substitute Danny Welbeck in the 88th minute.
"Credit to Watford, they created few chances, but took them all. It's sad because we gave everything."
Triumphant in the FA Cup in 2014 and 2015, Arsenal were beaten in the competition for the first time since a 1-0 fifth-round defeat by Blackburn Rovers in February 2013.
It left them facing the prospect of a trophyless season, with Wenger's side - booed off at the final whistle - eight points off the pace in the Premier League and 2-0 down to Barcelona ahead of Wednesday's Champions League last 16 return leg at Camp Nou.
Wenger named a strong team to for the visit of Watford, but despite dominating possession Arsenal struggled to create chances in the first half, with Mohamed Elneny sweeping one effort over the bar.