Marek Hamsik gave Napoli Champions League hope, but shambolic defending saw Athletic Bilbao win the play-off 3-1.
The first leg ended 1-1, so the Partenopei needed at least a goal to have any hope of going through to the Champions League group phase. Instead, they will go into the draw for the Europa League, leaving Juventus and Napoli in the top tournament.
Faouzi Ghoulam and Dries Mertens stepped in for Miguel Angel Britos and Lorenzo Insigne, but Gokhan Inler was again dropped in favour of Walter Gargano. Athletic defender Mikel Balenziaga shook off a knock to start.
Athletic hadnít reached the Champions League for 16 years, but Gonzalo Higuain scored nine career goals past this team and was immediately targeted by the passionate crowd. It was the first game with the all-new San Mames following restructuring work.
Jose Callejon ballooned an early chance well over, while Aritz Aduriz was incorrectly flagged offside and Rafael had parried with his legs anyway. Higuainís sudden snapshot was just wide, but Carlos Gurpegi was allowed a free header from a corner and incredibly steered it off target.
Athletic stepped up the pressure and a couple of Rafael errors werenít pounced on, as Aymeric Laporte volleyed over an open goal from four yards on his weaker foot.
An irritable Higuain was booked for dissent and Napoli wasted some promising set plays. It was 0-0 at the break, which put Athletic Bilbao in the driving seat on away goals.
Within 90 seconds of the restart, Napoli had broken through with that crucial strike. Marek Hamsik controlled on the edge of the box and hit a low drive through a crowd of legs into the near bottom corner. This made it 2-1 to the Partenopei on aggregate, but history said no Italian team had ever won at the San Mames.
Rafael flew to beat a Balenziaga screamer out from under the crossbar with a fantastic one-handed save, then Iraizoz came tearing out to clear from Mertens. Ghoulam was forced off by a wrist injury, making way for Britos as a makeshift left-back.
Napoliís terrible defending from corners proved fatal again, as Aritz Aduriz was left totally unmarked with the time and space to control and prod in from six yards. The Athletic players smartly organised blocks in the middle and Aduriz was smart to sneak away from the pack.
This left it at 2-2 on aggregate and all level on away goals, so it would go to extra time if the score remained like this.
Higuain cut in to find space, firing straight at Iraizoz, but Napoli literally gifted another goal to Athletic. Raul Albiol hit a fresh-air clearance and Rafael had rushed off his line with poor timing, allowing Aduriz to waltz into an empty net. It was absolutely shocking defending en masse from Rafa Benitezís men.
The Partenopei fell apart and allowed a third goal, as Aduriz was offside and ran towards the ball, but stopped just short of making contact, allowing Ibai Gomez to fire in while Napoliís defenders complained.
Unai Lopez tested Rafael from distance and it shouldíve been 4-1, but Aduriz incredibly side-footed his chance at a hat-trick over from six yards.