Mikel Arteta targets more silverware after extending his Arsenal contract until 2030
That finished off a lovely move involving Martin Odegaard, Bukayo Saka and Declan Rice, and it proved to be the decisive moment in a tough match for Arsenal.
Guimaraes was particularly impressive after he was introduced, as he was when brought on at half-time against Sunderland last month.
Asked whether his latest moment of individual quality was further evidence that signing him was £75million well spent, Arteta was quick to point out how much more he expects from Guimaraes.
"This is the level for Arsenal. Every week, every game, every minute, every action, you have to be at that level.
"At Brighton he wasn't, today was much better. He can still be much better than the game's he has done.
"That's what we have to demand. This is what I demand of myself. I'm going to demand the same of the players, because if we do that it will raise the standards and we will be a better team."
Guimaraes started only one of Brazil's three matches over the international break, as Carlo Ancelotti's side travelled to Australia and India.
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The start to his Arsenal career has been hindered by a couple of minor injuries, coming off a summer in which he had an extended break after the World Cup before joining the Gunners only a couple of weeks before the start of the season.
Explaining why Guimaraes has had limited starts in the league so far, Arteta said: "The reality is that he went to Australia, then to India.
"He's still not in the best condition because he hasn't had a pre-season. So we thought ok, [start] the players that are more settled here.
"If we have to bring him in and change the game, do it. We play again on Tuesday night, then on Sunday. We know it's going to be a lot of demands for everybody so we better manage that well."