Arsenal boss Mikel Arteta admits Nottingham Forest's fight-back was a concern yesterday.
Arsenal held a 2-0 lead to halftime, but Forest staged a nervous finish after a late goal for Taiwo Awoniyi.
Arteta said: "For sure, it's going to be very difficult to dominate games for 100 minutes. But we allowed them to get some grip of the game because they didn't create anything but on that action the game changes.
"Momentum shifts immediately after that goal. That's not the moment to change it, you cannot change it, now you have to be so good at dealing with that situation, running the clock down and earning the points. The team has done that really well but we're going to have to be more ruthless and more critical of ourselves to be more pushy and kill the game.
"That's my job - to create bigger problems to the opponent than the ones they are creating us and to play the best possible way to earn the right to win the game and have the highest possible probability to win the game. In order to do that we have to pick the right players to win the game every week - not only to start but also to finish. The players that come in during the final part of the game really helped us as well to win the game."