It proved to be the only goal of the game as interim manager Ralf Rangnick kicked off his time at the Red Devils with three points.
United dominated possession throughout the game, finishing the match with 61 per cent of the ball, and Vieira was left frustrated at how his side played when given the chance to keep it.
“It wasn’t our best performance,” he said. “We defended well as a team but in possession we weren’t brave enough. I strongly believe there was space for us to play better.
“I thought the game would end as a draw; both teams didn’t create many chances. When we had the opportunity to score through Jordan [Ayew], we didn’t take it and we got punished straight away.
“This is the higher level, we need to learn, we need to learn fast.
“When you look at the number of chances they created, I think a draw would have been a fair result.”