APOEL Nicosia booked their place in the group stages of the Champions League for the first time with a 3-1 win at home to FC Copenhagen.
The Cypriot champions had begun the second leg of their play-off a goal down, but were on level terms after just two minutes in when Kamil Kosowski netted.
They then stormed ahead in the tie after 18 minutes when veteran midfielder Chrysis Michael scored from the penalty spot, but the match took another turn four minutes later.
Copenhagen's Senegalese striker Dame N'Doye found the net to make it 2-2 on aggregate, which at that stage was enough for the Danes to progress on away goals.
But a first-half of see-sawing fortunes swung back APOEL's way after 41 minutes when Michael netted his second.
The home side held on to their advantage after the interval to secure a historic result.
Fiorentina had to come from behind to secure their passage on away goals following a 1-1 draw with Sporting Lisbon at the Stadio Artemio Franchi.
The Viola were in pole position after their 2-2 draw in the Portuguese capital a week ago, but a superb Joao Moutinho free-kick with 35 minutes played left the Italians chasing the game.
The hosts had mustered little in the first half, but came to life after the re-start mainly due to the play of substitute Stevan Jovetic, who netted the key goal after 54 minutes.
Arsenal were barely made to break sweat as they cruised to a 3-1 win over Celtic to complete a 5-1 aggregate triumph.
Eduardo's opening penalty may have been debatable, but Tony Mowbray's men hardly tested the Gunners before or afterwards, with Emmanuel Eboue adding a second following a crisp move after 53 minutes.
Andrey Arshavin came off the bench to add another after 74 minutes, before Massimo Donati pulled one back in injury time with a volley that went in off a post.
Striker Kostas Mitroglou scored the only goal of the game eight minutes from full-time to complete a comfortable night for Olympiacos as they progressed past Moldovan champions Sheriff Tiraspol 3-0 on aggregate.
Stuttgart also enjoyed a trouble-free evening at the Mercedes-Benz Arena as they played out a lifeless goalless draw with Timisoara to go into Thursday's draw with a 2-0 aggregate victory.
Markus Babbel's side had effectively done all of the hard work in Romania a week ago and spent 90 minutes controlling their advantage against a timid Timisoara side.
The visitors rarely threatened to find a route back into the game and it was their hosts who came the closest to scoring when Sebastian Rudy hit the post in the 58th minute.