Mikel Arteta had a warning for Bernd Leno and Arsenal after the goalkeeper's mistake almost proved costly in Thursday's clash with Rapid Vienna.
Two goals in four minutes from David Luiz and Pierre-Emerick Aubameyang secured a 2-1 win to start the Gunners' Europa League campaign after Taxiarchis Fountas had put the home side ahead in Austria.
Fountas had capitalised when Leno's poor touch and kick gifted him a chance to open the scoring, and two further poor pieces of play from the Arsenal goalkeeper gave the Greek striker opportunities he could not convert.
Leno has now made eight errors leading to goals in all competitions since the start of the 2018-19 season, the third-highest tally by any Premier League player behind David de Gea (nine) and Jordan Pickford (11).
Arteta will not discourage his side from trying to build play from the back, but he does accept there are occasions when clearing their lines is more important.
"It's part of our game," he told reporters. "We need to understand when we can do that and when we should kick the ball into the stands.
"They will understand better and better the type of balls we have to play in those areas and to who in relation to the pressure that's coming.
"We knew it was going to be a difficult match. We made it harder in the beginning with the goal we conceded.
"I really like the reaction. The second half, we understood much better the spaces we have to attack.
"In general, we scored two good goals, the second was fantastic. We are delighted to start with victory."
Thomas Partey made his full debut for the Gunners and delivered an accomplished performance at the heart of midfield.
The £45million signing attempted 57 passes in the opposition half, more than any other player, while some shrewd defensive work saw him win five tackles and regain possession eight times.
"I think he held the midfield by himself in the second half as well, when we were a little bit more open and we started to take more chances attacking certain spaces with some players," Arteta said.
"But I think he was fantastic tonight and there is much more to come from him. We know, with the price we paid for him, he's going to have a lot of people looking at him."