London - A remarkable late collapse scuppered Arsenal's hopes of qualifying early for the Champions League last 16 as Aleksandar Mitrovic's 90th-minute goal earned Anderlecht a deserved 3-3 draw in Group D on Tuesday.
A win would have ensured a place in the knockout rounds for the 15th season in succession and Arsenal appeared home and dry with fine goals by Alexis Sanchez and Alex Oxlade-Chamberlain building on Mikel Arteta's 25th-minute penalty.
But Anderlecht, deprived of three points a fortnight ago when Arsenal struck twice late on for a 2-1 victory, produced a late sting on a rainy night in north London, scoring three times in the last 29 minutes to keep alive their remote hopes of progressing.
Anthony Vanden Borre began the salvage job in the 61st minute before he converted a penalty to induce jitters in the home crowd. Substitute Mitrovic's late header then completed an astonishing comeback for Besnik Hasi's youthful side.
After seeing the door to the knockout rounds slammed shut, Arsenal can now realistically only hope for the runners-up spot as they have seven points to the 12 of Borussia Dortmund with two games remaining.
Belgians Anderlecht have two and Galatasaray prop up the table with one.
“We showed today we come from a small competition but we showed for the second time we can compete with these type of teams and in two games we deserve more than one point,” coach Hasi told reporters after spending time on the pitch saluting his celebrating fans.
Arsenal boss Arsene Wenger accused his side of assuming the job had been done.
“We had some bad luck, the first goal was offside, but we had a lack of concentration and thought the game was won,” the Frenchman said.
“Overall we were poor defensively from the first to the last minute. At 3-2 you have to secure yourself and we were not cautious enough.
“It was very poor defending. Am I angry or disappointed? Both,” said Wenger.
On a chilly, damp night it was Anderlecht who enjoyed the better of the opening stages with their quick interchanges causing several anxious moments in the home rearguard.
Arsenal were sloppy in possession and Dennis Praet, who was on the books of the north Londoners as a teenager, nearly scored on the counter-attack with a shot that spun wide after a hefty deflection off Gunners defender Per Mertesacker.
It was a warning shot for Arsenal and they were given another scare a few minutes later as the Belgians sprung forward again in menacing fashion.
Arsenal's first real chance saw Aaron Ramsey denied a certain goal when his shot from a Sanchez pass was blocked by a superb last-ditch tackle.
The hosts were playing a dangerous game though and Anderlecht looked more than capable of capitalising with Sacha Kljestan forcing a sharp save from Wojciech Szczesny.
Arsenal's opener then came out of the blue.
Danny Welbeck tussled with Chancel Mbemba in the area and when he went crashing to the ground, referee Clement Turpin pointed to the spot.
Captain Arteta, who later went off with a hamstring injury, coolly dispatched the penalty to bring up Arsenal's 500th goal in the Emirates Stadium.
A few minutes later Chilean marksman Sanchez grabbed his 10th goal since joining from Barcelona in the close season, lashing a ferocious right-foot drive past Silvio Proto after his initial free kick hit the wall and rebounded back to him.
When Oxlade-Chamberlain went through to slide in Arsenal's third goal after 58 minutes it appeared to be game over - but Anderlecht were not finished.
Three minutes later a suspiciously offside-looking Vanden Borre converted from close range and the bearded defender gave the visitors real hope when he slotted home a 73rd-minute penalty after Nacho Monreal wrestled Mitrovic to the ground.
Re-energised, Anderlecht had a couple of late opportunities, the best of which fell to Frank Acheampong as his fierce shot grazed the top of the crossbar.
Just when Arsenal were breathing a sigh of relief, Andy Najar's cross was glanced in by Mitrovic to send the visiting fans behind the goal wild with delight. - Reuters