Cristiano Ronaldo declined the opportunity to take Manchester United's penalty against Arsenal that Bruno Fernandes missed.
Ronaldo had converted spotkicks against Arsenal and Norwich earlier this season but missed his last penalty in regulation time in the FA Cup fourth round against Middlesbrough. Ronaldo still converted in the shootout.
Fernandes stepped up and missed his second penalty of the season to spurn the chance to equalise at 2-2. Fernandes was then at fault for Granit Xhaka's clincher in the 70th minute that sealed a 3-1 win for Arsenal.
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"I spoke with him after the game and asked him," Rangnick said of Ronaldo's decision not to take the penalty, "and he said he just didn't feel he should take it and that's why he said it would be better if Bruno took it."
Diogo Dalot hit the crossbar and the post either side of the interval, Ronaldo had a goal disallowed for offside and United wasted other chances in a game they had 14 attempts on goal.
Rangnick was satisfied with the improved performance on the 4-0 thrashing by Liverpool on Tuesday but despaired at United's defending in a week they conceded seven goals.
"I think we showed a response, an improved performance compared to the game at Liverpool," Rangnick added. "But still we gave away an easy goal, an early goal, far too easy, the way we defended in that moment, we had two or three chances to clear the ball.
"But we didn't and after being 1-0 down after four minutes in a game like this didn't make life easy for us. But I think the reaction we showed after that was good, we had numerous chances to score ourselves,- we hit the crossbar, we hit the post twice, apart from that we had enough chances to score three or four goals.
"And we were also pretty unlucky with the VAR decisions, there were three or four questionable VAR decisions after seeing the video footage in the locker room.
"But, again, it's about the result and the result was disappointing. Right now, our biggest problem was defending in and around the box. The last three games, on average, we conceded three goals and this is just too much."
