Crystal Palace manager Alan Pardew felt Marcos Rojo deserved to be sent off for his two-footed tackle during Manchester United's win on Wednesday.
Zlatan Ibrahimovic netted an 88th-minute winner as United trump Palace in a match overshadowed by controversy.
Rojo's lunge on Wilfried Zaha was among the contentious incidents, with the United defender only booked, having also been fortunate to be yellow carded for a similar challenge on Everton's Idrissa Gueye almost a fortnight ago.
Reflecting on the tackle, Pardew said: "From the sideline it did look bad.
"He jumps two footed and we've been to all these meetings where that's a red card."
Pardew was also left frustrated by United's opening goal on the stroke of half-time.
Paul Pogba put United ahead after Ibrahimovic appeared to use his arm to deflect the ball into the path of his French team-mate, while there were also suggestions the former was in an offside position when he tucked the ball beyond Wayne Hennessey.
"The first goal was a call the linesman should have seen," Pardew added. "I thought it was offside even from where I was standing. He refereed the game aggressively, I thought. There were a lot of fouls in the game, it could have flowed a little bit more."
Palace are now 16th in the table, just three points above the relegation zone, having won just one of their last 10 matches.
Pardew, however, remains upbeat about his team's chances following their performance against United at Selhurst Park.
"I have to look at my team and say they were committed tonight," he said. "We tried to make it very difficult for Man Utd. Offensively, I think we could have done a little bit better in the first half in certain situations.
"We certainly deserved to come in 0-0, the decision was a tough one for us, a couple of bad decisions in that first half.
"Second half we had a good little spell, got a great goal and it was a shame we couldn't kick on from there. In the end we were undone by two of their best players and I just feel for my team because they gave me everything tonight."