Declan Rice’s corner kick led to Jurrien Timber s decisive goal in the 2-0 Premier League win.
Rice, who has provided 10 assists in the league since joining Arsenal, attributed his confidence in taking corner kicks to his team s reduced gap with league leaders Liverpool to seven points.
"Tonight, I just had a different energy. I just wanted to do anything for the team to win and in the second half, I would have done anything tonight to get the three points. I’m buzzing," Rice told Arsenal s official website.
"I think that every time I was going to take the corner, I knew it was going to be a good ball. In my head, I was just thinking about putting it in the same spot and in the end with repetition, you end up scoring goals."
"This year has been my biggest output in terms of goals and assists throughout the year, so I’m really happy with that," said Rice, who has continued playing despite suffering a broken toe last month.
Bukayo Saka s corner kick set up Arsenal s second goal of the match, with United coach Ruben Amorim saying the hosts set pieces killed the game.
Third-placed Arsenal visit Fulham on Sunday.