Alexandre Lacazette scored a crucial away goal to give Arsenal a 1-0 win over Olympiakos in Europa League round-of-32 action on Thursday.
The match at Georgios Karaiskakis Stadium had been a cagey stalemate until the 81th minute when Bukayo Saka served a nifty low cross into the middle of the box for Lacazette's easy finish.
The Greek side's best chance had come five minutes before the lone goal when Bernd Leno failed to manage Mathieu Valbuena's well-struck free-kick, but was able to pounce on Youssef El Arabi's second effort.
Lacazette's goal made up for an earlier inexplicable miss when the Frenchman somehow shot wide from about eight yards having a solid build-up by Gabriel Martinelli.
"It was a good performance. We had a clean sheet, that's a good point," Lacazette told BT Sport after the match. "We wanted to score more goals but in the end it is good because we have an advantage for the second leg.
"I had a few chances but it's not always easy to score. Thanks to Bukayo Saka for the assist, it was nice. I'm happy to score."
Sokratis Papastathopoulos almost doubled Arsenal's lead when his late header ricocheted off the crossbar. The Greece international was later substituted off after twisting his knee on a challenge.
Arsenal manager Mikel Arteta praised his side's stellar defence and for notching their third straight clean sheet.
"It's tough to come to a stadium like this and come away with a win," Arteta said. "There are some great things for our development as a team. The first 10 minutes we suffered and were completely poor.
"I told them they have to enjoy defending. If you give the ball away you better run back. The team instead of splitting are coming together and the wide players are doing different things than before. It's a big effort."
Arteta also singled out the 18-year-old Saka for his performance and his role in creating the game winner.
"I'm really pleased with the way he's developed and the way he's handled this situation," Arteta said. "He's also asking questions, willing to improve, he's a makes big decisions in the final third which is a big gift."
The return leg will be at Emirates Stadium on Feb. 27.