Gyokeres, who was signed from Sporting Lisbon in the summer for a reported fee of £64m following a lengthy pursuit, grabbed a brace against the Black Cats after replacing Gabriel Jesus in the 60th minute as Arsenal stretched their lead at the top of the Premier League to nine points.
Speaking to the press post-match, Arteta marvelled at the performance of the Swede.
“He was ready straight away, and when he got the line-up and he wasn’t in [starting], everyone reacts in such a way because we know – we have to experience this every three days – how important the finishers are,” said Arteta. “The impact they are having on the team, the result and where we are at the moment. I’m very happy.”
Gyokeres has experienced a difficult start to life in north London, but eight goal contributions from his last eight appearances in red and white have put to bed some concerns about his confidence in front of goal.
“He is the type of character that we expected, and when you put that shirt on, it comes with lots of responsibility and huge expectations,” Arteta told the press.
“You need to live with that. In your journey here, you’re going to have moments where it goes really well and others where it’s going to be tough. When you have an opponent that plays a part and one that makes it very difficult for you, but I love his character and the way he approached every single day.
“He is so focused on the pressing, and he knows what he has to do. He has a genuine will to help the team in whatever role he has. I am very happy [with Gyokeres].”
Arteta opted to start Jesus ahead of Gyokeres against Sunderland, something many strikers may have taken a confidence blow from as a result.
But the Arsenal boss was defiant on his decision, insisting Gyokeres had the confidence to come on and make an impact following goals against Inter Milan and Kairat Almaty before notching against Leeds United last weekend.
“When you feel confident, when you feel your best, that’s when you can really take your game to the highest level. We all try, but firstly the team and then the staff, obviously," he added. "We are really behind him, and we try to help him and try to support him, and he is delivering. He is in a really good moment now.”
Arsenal now sit nine points clear at the top of the Premier League before Manchester City look to close the gap back to six as Pep Guardiola’s side travel to Anfield on Sunday to face Liverpool.