Roy Keane agrees with Ralf Rangnick about Manchester United's biggest problem

Roy Keane has agreed with interim manager Ralf Rangnick that wasteful Manchester United are the architects of their own downfall, speaking in the wake of Friday evening's FA Cup defeat to Middlesbrough.

Following a 1-1 stalemate at the end of 120 minutes at Old Trafford, United's FA Cup adventure came to an end following an 8-7 penalty shootout triumph for the visitors, with Anthony Elanga missing the final spot-kick.

The two teams traded 15 successful penalties before Elanga was left with the responsibility of keeping the shootout going and trying to help United maintain their ambitions of reaching round-five.

However, he fired his effort over the bar, leaving the 9,000-plus army of Middlesbrough supporters in raptures behind the goal at the other end of the pitch.

United, who took the lead in the first half through Jadon Sancho's first half goal, wasted a plethora of chances to put the tie to bed before half time, including a missed penalty from Cristiano Ronaldo.

"We gave away too many chances, especially in the first half," said Rangnick, reflecting on United's failure to convert their chances.

"We should and could have easily been up 3-0 after 45 minutes and even in the second half we missed some great opportunities, even after they scored their goal that shouldn't have stood.

"But Bruno's chance was almost like a penalty as well, so we have to blame ourselves for giving away and wasting too many opportunities in the game.

"And, in the end, if it's on penalties it's also a question of luck and in the end we lost that game and we are all incredibly disappointed."

The United chief's assessment matched that of Keane, who was part of the punditry panel for ITV Sport's coverage of the contest.

The former midfielder