Ange Postecoglou got a harsh reintroduction to the Premier League with new team Nottingham Forest as Arsenal’s new signings Martin Zubimendi and Viktor Gyokeres combined to secure a 3-0 win on Saturday.

Zubimendi, the Spain defensive midfielder recruited from Real Sociedad, volleyed home spectacularly from the edge of the area in the 32nd minute to put Arsenal in front before Gyokeres tapped in a cross from Eberechi Eze — another summer signing — to double the lead inside the opening minute of the second half.

Zubimendi headed in the third in the 79th minute to complete a miserable return to English soccer for Postecoglou, the former Tottenham manager who was hired by Forest on Tuesday as a replacement for the fired Nuno Espírito Santo.

“This week, it’s fair to say, was fairly disruptive for the players,” Postecoglou said. “International week as well, so they didn’t get in until Thursday, Friday — they see a new manager and I’m trying to implement new things.

“So it’s only understandable that they probably haven’t got clarity of thought at the moment. But that’s my job to try to bed that (in) over the next few weeks.”

Arsenal has won three of its first four games, losing the other to likely title rival Liverpool.

Postecoglou was fired by Tottenham in June despite Spurs winning the Europa League title and securing qualification to the Champions League. Domestically, though, Tottenham finished 17th, just one spot above relegation.

Forest offered little at Emirates Stadium aside from a chested effort from Chris Wood that Arsenal goalkeeper David Raya tipped onto the crossbar.

Otherwise, it was all Arsenal despite manager Mikel Arteta being without star players Bukayo Saka and William Saliba because of injuries, starting with Declan Rice on the bench and seeing captain Martin Odegaard go off in the 18th minute with a suspected shoulder injury.