Antonio Valencia has apologised to Manchester United 's players and fans after his mistakes helped Arsenal dump his side out of the FA Cup in Monday 's quarter-final defeat . The cup exit effectively ended any hopes of silverware ended up at Old Trafford this season - and Valencia more than played his part in a dismal display from Louis van Gaal 's side . The midfielder-cum-defender put in a weak challenge and allowed Alex Oxlade-Chamberlain to set up Nacho Monreal for Arsenal 's first before playing a poor backpass to set up Danny Welbeck for his second-half winner . Antonio Valencia was poor for Manchester United on Monday night and was at fault for two goals . The midfielder-cum-defender inexplicably let Danny Welbeck in for the winner with an awful backpass . Nacho Monreal ( left ) scored Arsenal 's first , with Valencia involved in the defensive collpase . Valencia posted this lengthy apologies to his team-mates and supporters after the defeat by Arsenal . Valencia was panned by fans and television pundits alike for his awful performance , and the 29-year-old has now offered up an apology for his showing . ' I want to apologise to my team-mates and the fans of Manchester United , ' Valencia said on Instagram . 'Tomorrow is another day and keep working , ' he added before tagging team-mates Marcos Rojo , Juan Mata , Ander Herrera , Rafael and Robin van Persie in the message . Valencia tries to get close to Chile winger Alexis Sanchez during Monday night 's FA Cup defeat . Former United captain Roy Keane called Valencia 's defensive contribution 'disgraceful ' and accused the Ecuadorian of 'downing tools ' in his television analysis . And things got even worse for Van Gaal 's first choice at right back on Tuesday when Rafael put in a brilliant - and goalscoring - performance for United 's Under 21s to pile the pressure on Valencia ahead of Sunday 's Barclays Premier League clash with Tottenham Hotspur . Rafael ( left ) was excellent for United 's Under 21s , scoring and looking a viable alternative to Valencia .
Antonia Valencia has apologised for Manchester United 's dismissal by Arsenal . villa was at fault for both incidents , including mark Welbeck 's winner . Roy Keane called the midfielder - cum - defender ' disgraceful ' in his analysis . Rafael put pressure on Valencia 's position with a goal for United Under United . villa HERE for all the latest Manchester league news .