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.
Holders Arsenal were dumped out of the FA Cup by Watford on Sunday. Goals by 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 Monday’s semi-final draw.
“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 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.
Arsenal centre-back Gabriel, meanwhile, was very fortunate to escape without even a booking after flying into a two-footed challenge on Troy Deeney with his studs raised.
Watford made the breakthrough in the 50th minute as Deeney flicked a left-wing throw-in to Ighalo, who turned, held off Gabriel and beat David Ospina with a low shot.
The visitors extended their advantage 13 minutes later in stunning fashion as Guedioura met Deeney’s lay-off with a blistering strike that flew from his right foot into the top-right corner.
Welbeck reduced the arrears late on, finishing neatly after a one-two with Mesut Ozil, but then squandered a golden chance to equalise by shooting wide of an open goal from Kieran Gibbs’s pass.
“I have memories on television of the old Wembley and watching in Spain and seeing the finals of this competition,” said Watford’s Spanish manager Quique Sanchez Flores.
“Now it is a new Wembley. I’ve just arrived in England and to get there is exciting. I’m really happy for the fans and they deserve this kind of day.”
Reeling from last Thursday’s 2-0 loss at Liverpool in the first leg of their Europa League last 16 tie, United welcomed West Ham to Old Trafford needing victory to rekindle their season.
But Slaven Bilic’s visitors made the better first-half chances, with Emmanuel Emenike shooting wide from Andy Carroll’s lobbed pass and heading straight at David de Gea from Aaron Cresswell’s cross.
West Ham took the lead in the 68th minute when French playmaker Payet confirmed his status as one of the players of the season by arcing a picture-perfect 30-yard free-kick over the wall and in off the left-hand post.
But with nails being chewed to the quick by the home fans, Martial kept United in the competition by charging in to convert Ander Herrera’s right-wing cross with a close-range volley.
Michail Antonio almost restored West Ham’s lead in stoppage time, but De Gea turned his low strike around the post to send the tie to a replay.
“We have played a game against Liverpool on Thursday and they (West Ham) had the whole week to prepare and (yet) we could come back and show a big revival,” said Van Gaal.
“I have to give a lot of compliments to my team. They were mentally tired after Liverpool and also in the body.”
A bullish Bilic told the BBC: “Manchester United are a different team when they play away and don’t have that confidence.
“It (the replay) is going to be a tough game, but I fancy us because we’re going to be even more confident.”