Arsene Wenger denied that Arsenal would have beaten Sunderland with Robin van Persie in their side after a goalless draw at the Emirates Stadium.
Van Persie completed a £24m move to Manchester United on Friday with his place in the starting XI taken by new signing Lukas Podolski and, despite the Gunners having plenty of the ball, there was a lack of quality in front of goal.
The best chance of the game fell to new signing and substitute Olivier Giroud, but the former Montpellier striker shot wide to leave Wenger frustrated.
"We played with a good spirit, were serious and we put the effort in, but we lack sharpness and fluency at the moment to be dangerous in the final third," he said.
"The few chances we had, we could not convert them.
"Sunderland defended very well for the whole game, and we lacked something - sharpness, also quality and accuracy in the final pass."
Wenger also believed it was impossible to say that Van Persie would have changed the result, adding: "You can never check that. We have played some draws at home with Van Persie, we have lost some games with Van Persie as well.
"However, it is true that last year in every game he found something special. I never denied that we lost a world-class player, that is very difficult to replace."
Spain international Santi Cazorla, however, showed he could well prove to be one of the signings of the summer having joined from Malaga.
Wenger said: "It is difficult not to be pleased with him because he played on Wednesday night, the whole [international] game in Puerto Rico. All the chances were created by him, basically."