Olivier Giroud’s opening goal was the catalyst for Arsenal to power past Swansea, according to Arsene Wenger.
The Gunners struggled for inspiration in the opening 40 minutes as the hosts stifled the title chasers, but Giroud's finish from close range just before the break was a turning point in the game.
Mesut Ozil's header struck Alfie Mawson to present Giroud with the simplest of tasks to convert his 10th goal of the season and his fifth goal in his last five games.
"Olivier has scored some important goals and today’s was another one," said Wenger.
"We didn’t create much in the first half so it was important to take that opportunity."
Giroud's celebration was low-key to say the least as he seemed to twist his ankle in the build-up. He was replaced on 60 minutes and he was seen with heavy strapping on his right ankle while he was on the bench.
"It’s an ankle problem - I don’t know how serious it is - we’ll have to assess it," said Wenger.
Another Arsenal player that scored but ended the game on the bench was Alexis Sanchez.
Sanchez got in on the act with his 14th goal of the season to make it 4-0 but looked frustrated to be substituted by Danny Welbeck with 10 minutes to go.
Wenger downplayed his sulky attitude though, saying: "He never looks happy when he comes off because he loves to play."
"He had a good rest. We have some good players like Danny Welbeck coming back and it was an opportunity to bring him into the competition. Overall Sanchez did well today - he worked hard."
For the first-half Swansea fought tenaciously and stopped Arsenal having a meaningful sight of their goal and Wenger admitted the relegation-threatened Swans made life tough for his team.
"It was a very intense first-half from both sides - Swansea went for it and were well organised," he said.
"They gave absolutely everything and contained us very well. In the second half we started to take over and create chances. We were a bit fortunate in the goals we scored but we were always dangerous in every transition."