Roy Keane called Manchester United's Antonio Valencia 'disgraceful' for his part in both of Arsenal's goals in the FA Cup quarter-final at Old Trafford on Monday. Valencia's short backpass gave Danny Welbeck the chance to score Arsenal's winner by rounding David de Gea, and the former United captain thought he was poor. Keane was also annoyed at Arsenal's opening goal which saw Alex Oxlade-Chamberlain ride three challenges before setting up Nacho Monreal  with Daley Blind and Valencia at fault. Roy Keane was very critical of Manchester United's Daley Blind and Antonio Valencia on Monday . A poor defensive showing from United allowed Nacho Monreal to score Arsenal's first-half opener . The former United skipper is known for his outspoken views and made it clear that the pair were not fulfilling their responsibilities. 'It’s too open some times – it was a shocking goal to concede,' Keane said. The former United captain had told presenter Gary Lineker not to ask him about United's defensive efforts for Monreal's opener and when the subject was mentioned he was highly critical. 'I'm looking at it in terms of the defending, and character and putting your body on the line,' Keane added. 'The lads have just downed tools there. Blind goes in for a challenge on Alexis Sanchez at Old Trafford but his work for the goal was criticised . Valencia was panned for his 'absolutely disgraceful' contribution which Keane called a 'schoolboy error' 'Blind and Valencia - it's absolutely disgraceful. Schoolboy errors and that’s what costs your team. Big moments in a football match and if you give Arsenal, with the quality that they have, that type of freedom that’s what happens. 'It was too easy, shocking. Absolutely disgraceful.' Valencia was also at fault for Arsenal's second, laying a goal on a plate for former United striker Danny Welbeck with a under-hit back pass to David de Gea. Keane said the freedom given by the players to Alex Oxlade Chamberlain was poor . David de Gea could have taken out Danny Welbeck and taken a red card as a sacrifice said Keane . 'Shocking defending, this is even worse (than the first goal,' Keane added. '(Phil) Jones, there's a time to clear, he can do better and Valencia of course is compounding from the first goal.' And Keane felt David de Gea maybe would have been better served taking out the goalscorer and accepting a red card. 'Maybe the goalkeeper should sacrifice himself and take Danny out,' he said. 'Sometimes you need to sacrifice.'
Roy Keane was appearing as a pundit for the BBC at Old Trafford . He criticised Daley Blind and Antonio Valencia for their poor defending . Nacho Monreal scored  after a run from Alex Oxlade-Chamberlain . Valencia then played a poor backpass for Danny Welbeck's winner .