Mikel Arteta lamented Arsenal making the closing stages "difficult" in the 1-0 win over Zurich that sealed Europa League Group A top spot on Thursday.
The Gunners registered their ninth home win in as many games across all competitions this season, their longest such run at the start of a campaign since 2009-10 (11), after Kieran Tierney's first-half winner.
Arsenal also kept a clean sheet in all three of their home group games in Europe for the first time since the 2008-09 Champions League, owing to a resolute defensive performance at Emirates Stadium.
Arteta suggested his side were at fault in the latter parts of the game, though, bemoaning the hosts for inviting pressure on themselves as Adria Guerrero saw a second-half equaliser disallowed.
"We always try to start faster. We have an opponent that has something to say in the game," the Arsenal manager said. "We made the game difficult in the last 15, 20 minutes."
Arsenal will take the positives from topping their Europa League group for a fifth time in as many attempts, with no side topping a pool more often since the rebranding of the competition in 2009-10.
But a second-half injury to Takehiro Tomiyasu somewhat marred the win, leaving the full-back as a potential doubt for the World Cup with Japan, who start their campaign against Germany in 20 days.
"He felt something," Arteta said of the Japan international's injury, though he refused to give a timescale on his return as he added: "We don't know yet.
"We have Chelsea at the weekend, that's my focus."
Tierney's sumptuous first-half strike was his third in the Europa League (two for Arsenal, one for Celtic), with only Kris Commons (six) netting more among Scottish players in the competition since 2009-10.
The left-back has had to play an understudy role to Tomiyasu for large parts of the season but insisted his performance levels will not drop, whether in the starting XI or not.
"We wanted to get the game done by 60-70 minutes and score a couple of goals, but we never did that," he told BT Sport.
"I thought we saw the game out. They put a lot of pressure on us but we saw it out well. We had to show fight and hunger because they came here with so much of that.
"We knew they would. Their last couple of results have been good so they have grown in confidence. We dealt quite well, it's just a pity we couldn't score a couple more.
"We won 5-0 a few days ago so it's not like this [struggling for a second goal] happens all the time. Teams win 1-0. As long as we get a clean sheet we are confident we will score.
"I want to play every game I can. I have to keep working hard. The manager knows I will give 100 per cent whether I start or not."