LONDON — Arsenal eased to a 4-1 victory over Crystal Palace in the Premier League on Saturday after striker Alexis Sanchez was left out ahead of his expected move to Manchester United.

The hosts were three goals ahead in 13 minutes and 4-0 up in 22 minutes through Nacho Monreal, Alex Iwobi, Laurent Koscielny and Alexandre Lacazette as Arsene Wenger's team moved within five points of the top four.

Monreal's afternoon came to a premature end later, though, when he limped off with a hamstring problem.

Wenger explained his reasons for omitting Chile forward Sanchez, who is likely to join United while midfielder Henrikh Mkhitaryan travels in the opposite direction in a swap deal.

"I didn't take him because there is a question of him moving to Manchester United and you cannot drive up north and as well play football," said Wenger. "That's difficult."

Wenger said the move wasn't yet "over the line."

"I expect it to happen maybe but I cannot announce it because in the next 48 hours it will be decided one way or the other. In these kind of things, as long as it's not over the line you cannot say it will happen because the negotiations become more and more longer and edgy because every detail becomes important nowadays."

Sanchez's firepower was not needed against an out-of-sorts Palace, which went behind after six minutes when Monreal headed in a corner by Granit Xhaka.

Monreal then turned provider for Iwobi as the Nigerian international stretched out to steer a low cross past goalkeeper Wayne Hennessey.

Arsenal made it 3-0 when Koscielny bundled the ball in. Mesut Ozil laid on the fourth goal for Lacazette, who scored for the first time since the 3-1 defeat to United on Dec. 2.

Luka Milivojevic produced a consolation strike for Palace with a sweet volley in the second half to deny Arsenal's veteran goalkeeper Petr Cech the 200th Premier League clean sheet of his career.

Palace midfielder Yohan Cabaye was taken off on a stretcher in the closing stages.