Gareth Bale almost adds a special sheen to the night as his free-kick is belted over the wall and dips viciously on target, forcing the Dinamo keeper to punch over.
Every Spurs fan holds their breath as Harry Kane holds his knee after being hacked down. I think he's going to be OK, but Jose Mourinho is taking no chances. Carlos Vinicius is immediately sent out to warm up.
The goal stands - as it should. Such a brilliant header. He took ownership of the opportunity in the box and applied a superb finish. A raft of Arsenal changes coming up.
VAR is having a check of that Arsenal goal, however, might have to put the celebrations on hold...
The cards are coming out now. Davinson Sanchez is into the book for a late challenge, shortly after Luka Ivanusec is yellow carded for pulling back Lucas Moura.
Back in front!
A corner is played short to Willian, who then lofts the ball into the box and Gabriel loops a great header into the far corner. Superb header.Copyright: Getty Images
Swiss striker Mario Gavranovic is on to try and find what would be a precious away goal for Zagreb. Bruno Petkovic departs.
Olympiakos make the first change as goalscorer Youssef El-Arabi is replaced by Ahmed Hassan. Mohamed Elneny looks to be the Arsenal player about to come on.
Oh, well done Ben Davies. He sticks out a leg to prevent a cross finding Lirim Katrati at the back post.
Rasmus Lauritsen dives in to meet the resulting corner but his header is blocked.
Willian tries his luck from distance but his shot goes wide.
Looks like both sides are considering changes to try and win this in the final 15 minutes.
'We give them nothing'. A battered and bruised Ndombele is withdrawn with Pierre-Emile Hojbjerg on to ensure that zero stays next to the Dinamo tally.
Bukayo Saka gets in behind the Olympiakos defence but he is forced wide. He cuts into the box but his shot hits an Olympiakos player.
Just under 20 minutes remaining.
I was just about to type that Tottenham could do with another goal and look who pops up.
Again, it is something of a gift for Kane, who is handed the ball in the box by a dire attempted clearance from Kevin Theophile-Catherine, who just prods Aurier's cross to the England skipper.
He actually makes the finish look a lot easier than it is, jinking and then firing in low.
The difference between 1-0 and 2-0 is huge.Copyright: Getty Images
Ndombele is in the thick if it again, this time to win the ball before being fouled by Ademi, who gets a booking for it.
Danger for Arsenal as Willian plays Lazar Randjelovic onside and his ball cross the box finds Youssef El-Arabi, who sweeps a shot just wide via a slight deflection off an Arsenal player.
Time for some changes. Gareth Bale, Lucas Moura and Steven Bergwijn on for Erik Lamela, Son Heung-min and Dele Alli for Spurs.
Lirim Kastrati and Iyayi Atiemwen join the action for Dinamo, with Lovro Majer and Mislav Orsic going off.
Almost immediately, Bale finds Bergwijn in the box with a lovely cross that the Dutchman volleys but straight at the keeper.
No player has made more errors leading to goals in the Europa League this season than Dani Ceballos (two), with his two errors coming in Arsenal's last two games.
There's been a third change for Olympiakos with Brumo replaced by Lazar Randjelovic and the hosts are now buoyed by that unexpected equaliser.
Matt Andrews: Commentator: arsenal look comfortable, only a mistake will see them concede. Ceballos: hold my beer.
Jon Dunthorne: If you are useless at playing out from the back, don’t play out from the back duh
As the saying goes, the definition of insanity is doing the same thing over again and Arsenal just keep repeating these defensive mistakes to give their opposition an easy goal.
It is a familiar pattern, miss a hatful of chances that should have seen them out of sight but instead they are level.
Ledley King is dishing out instructions to some Spurs substitutes. Bale is one of them, as is Bergwijn.
Meanwhile, Petkovic finds space in the Spurs box but fires his low effort wide. That was a good chance.