United's 3-0 win at Fulham earlier on Saturday had put them four points clear of the Gunners, who remain sixth - on the same points as fifth-placed Chelsea, who face Manchester City on Sunday (today at 4pm local time).
He was one of Arsenal's best players during Saturday's 2-1 victory over Huddersfield Town but it didn't seem to shield Alex Iwobi from criticism.
And the Huddersfield fans finally had reason to celebrate after four games without a goal as Kolasinac turned into his own net in the 93rd minute, while Leno then saved from Juninho Bacuna to protect Arsenal's victory.
Arsenal have also won the joint most points this season in the final 10 minutes of matches, but relying heavily on second-half turnarounds and late shows could only go on for so long.
"If we ask is it hard for us, I think it's hard, but we can".
When questioned about his sides capability of finishing in the top four, Emery was optimistic.
"Defensively they are one of the worst sides I've ever seen in the top six of the Premier League", former Arsenal midfielder Paul Merson said. We do our work to win every game and on Saturday we did the job.
"Every player worked very well and the last action, unfortunately for us they scored and also maybe they deserved it".
Unai Emery said he is not anxious that Arsenal failed to keep a first away clean sheet of the season, as first-half goals from Alex Iwobi and Alexandre Lacazatte secured a 2-1 win at Premier League bottom side Huddersfield.
We played against Arsenal, one of the top teams in the table and we had many chances.