Kai Havertz scored an 89th-minute penalty against his former side Bayer Leverkusen to rescue a 1-1 draw for Arsenal in the first leg of their Champions League last-16 tie at the BayArena.
The Gunners appeared to be heading for their first Champions League loss of the season after Robert Andrich's goal from a corner straight after half-time, but they were handed a reprieve when Malik Tillman was adjudged to have fouled substitute Noni Madueke.
The hosts were aggrieved by the decision but it was upheld after a lengthy VAR check, allowing Havertz, who had received a warm reception from the home fans after his introduction from the bench, to coolly convert an invaluable equaliser from the spot.
The Gunners went into the game having won all eight of their league phase fixtures but turned in a drab display overall and were breached by a set-piece goal reminiscent of one of their own when Andrich headed in Alejandro Grimaldo's inswinging corner.
The opener came just 45 seconds into the second period and followed a superb save by David Raya after Bayer Leverkusen had fashioned a chance for Martin Terrier straight from the kick-off.
Arsenal had gone closest in a tight first half, rattling the crossbar through Gabriel Martinelli following a slick break, but laboured offensively, especially after Leverkusen's opener, with Jurrien Timber heading one of few clear chances over the bar.
Havertz's penalty, won by one of few bright performers in Madueke, who made a positive impact following his introduction for Bukayo Saka, was only Arsenal's second shot on target of the evening. They finished the game having had only six shots in total.
Despite their poor showing, they will return to the Emirates Stadium for next week's second leg as favourites to advance thanks to Havertz's penalty as they continue their hunt for silverware on four fronts.
Arsenal boss Mikel Arteta to TNT Sports:
"The game had very different periods. We started well, had a massive chance, hit the crossbar with Martinelli. We had some dominance but didn't finish enough actions. They were quite dangerous with that.
"We didn't pay enough attention on the kick-off, and after they score the goal. We had to stay emotionally very composed, we improved with the changes and found a way to draw the match.
"They are the details. They have certain routines, we didn't do it, and we paid the price for it."
On Havertz's goal, he added: "Football has funny and nice stories, and it was really impressive the way Kai took the penalty, really composed. It was a big goal for us."
It is rare to see Bukayo Saka withdrawn as early as the 60th minute, especially with Arsenal needing a goal. But the winger had struggled badly. In a poor collective display, his replacement, Madueke, instantly provided some much-needed drive.
While Saka's super-power, on form, is the quality of his decision-making, Madueke can be frustrating to watch. He is unpredictable and often erratic. But he does at least guarantee directness and attacking threat. He gave Leverkusen problems.
The decision to award Arsenal's penalty split opinion. Leverkusen certainly felt it shouldn't have stood. But it came from that Madueke directness as he carried the ball into the box from the right, where at other times he was able to isolate Alejandro Grimaldo.
"I felt that we needed something else," said Arteta when asked about the change in his press conference. "Noni has been contributing and been a real threat and I decided to make the change." His impact, the Arsenal manager added, was "no surprise".
"Big credit to him for stepping in the manner he did." His cameo helped Arsenal turn what would have been a deflating defeat into a result they can build from in the second leg.
Arsenal winger Noni Madueke told TNT Sports: "We came here to try to win, but when you can't it's good to draw.
"We're fully confident heading back to the Emirates, we're confident we can get the job done back in London."
On the penalty, he added: "I felt contact, so I went down, penalty. I know Kai very well, he's been scoring high-pressure goals all his career. I had 100 per cent confidence in him.
"When you come on and your team is losing, you've got extra impetus to take risks. I tried to mix it up as much as possible.
"When you score in the last minute to draw it's a positive. We know we could have been better, but away to a top team, it's a positive result.
"Our basics could be better. On the ball we weren't as good at threatening their box, but we will show that in London, for sure."
Bayer Leverkusen boss Kasper Hjulmand in his press conference: "For me it's not a penalty.
"I think that sometimes the referee shouldn't blow the whistle, and then check with the VAR, then it's 100 per cent safe and secure. But if he whistles, then it's not clear and obvious. For me it just wasn't.
"It would have been better with a 1-0 victory but that's how it is. I don't see a penalty there but that's the way it went.
"Overall a good performance and we will travel to London next week full of hope."
Round of 16 second legs: March 17-18
Quarter-finals: April 7-8 and 14-15
Semi-finals: April 28-29 and May 5-6
Final: May 30 (Puskas Arena in Budapest, Hungary)
