With a second 5-1 rout in three weeks, Bayern Munich completed Arsenal's humiliation on a night of protests against manager Arsene Wenger.

Whether Wenger gets a chance to return to the Champions League next season remains unclear, as his latest contract will expire at the end of this season after 21 years at the club.

His team's heaviest-ever loss at the Emirates Stadium, completing a 10-2 aggregate loss on Tuesday as the German champions reached the quarterfinals, will only heighten demands by pockets of supporters for Wenger to go.

Asked if he will manage Arsenal again in the Champions League, Wenger replied: "I don't know ... I am here to talk about football not my future."

It is Wenger's failure to deliver Arsenal's first European Cup that has diminished his standing among fans who once lauded him as a coaching revolutionary.

For the seventh consecutive season, Arsenal has exited the Champions League in the Round of 16 and it has still only reached the final once, back in 2006.

Wenger deflected questions about his own future by reprimanding Tuesday's referee for what the Frenchman called "unexplainable and scandalous" decisions.

And there was no sympathy from Bayern, with the five-time European champions joining in the derision by tweeting: "What time is it? Yep, it's ten to!"

The night's other game saw the first-leg score replicated as Real Madrid beat Napoli 3-1 to reach the last eight for a seventh successive season.

But Bayern enjoyed such an emphatic advantage that Arsenal had an uphill task. A glimmer of hope, though, came in the 20th minute when Theo Walcott beat goalkeeper Manuel Neuer at his near post.

Nothing went Arsenal's way after that. Walcott was denied a potential penalty and then Koscielny was dismissed after the referee initially prepared to show the captain a yellow card for bringing down Robert Lewandowski 10 minutes into the second half.

"The game was difficult until the penalty," said Bayern coach Carlo Ancelotti, who is looking to win the Champions League with a third different club after successes with AC Milan and Real Madrid. "We were too open. They pushed as we expected. We were not so clear with the ball as we usually are."

Arsenal didn't do itself any favors, going into freefall as Bayern tore Wenger's side apart with a clinical attacking masterclass. Arjen Robben netted after a poor clearance by goalkeeper David Ospina in the 68th minute, and Douglas Costa added another in the 78th before Arturo Vidal scored twice in the space of five minutes.

"Bayern can be a good side but tonight they can also say thank you to the decisions of the referee," Wenger said. "It leaves me very angry, very frustrated ... (the referee) killed the game."

As Bayern marched into the quarterfinals for the sixth consecutive year, Arsenal cannot be certain it will even be back in the competition next season. Not only are the Gunners far from winning the Premier League for the first time since 2004 but they are out of the top four.

The objectives are clearer for Bayern: collecting a fifth successive Bundesliga title and winning the Champions League for the first time since its Wembley success in London in 2013.

"We just want to keep chugging along," Neuer said. "We don't intend on letting up."

Two quick-fire goals saw Real Madrid survive an early scare to win 3-1 at Napoli on Tuesday and reach the Champions League quarterfinals for a seventh successive time.

Trailing 3-1 from the first leg, Dries Mertens gave Napoli hope with a 24th-minute strike to send a packed San Paolo stadium into raptures. But Madrid captain Sergio Ramos headed in a Toni Kroos corner early in the second half and had another header deflected in by Mertens six minutes later to effectively end the contest.

Alvaro Morata wrapped up the 6-2 victory on aggregate for the holders by tapping in a rebound in stoppage time after Pepe Reina had denied Cristiano Ronaldo.

"We really suffered a lot in the first half, we couldn't do what we wanted to do, they were pressing us very high," Madrid coach Zinedine Zidane said. "Then we made changes in the second half and we were much better. It was completely different. We are happy.

"We knew the beginning of the match would be very hard ... but a match is 90 minutes and I think we did very well in the second half."

Napoli was left to rue its first-half profligacy which saw Mertens hit the post. Ronaldo, who is two goals short of becoming the first player to score 100 times in European competition, was also denied by the woodwork.

"We weren't only equal to Real Madrid for the first 55 minutes, we were better than them," Napoli coach Maurizio Sarri said. "We put them in a lot of difficulty and that's something to be proud of. We're very disappointed above all for the fans, because these fans deserved something more."

Ramos acknowledged that Madrid has a lot of work to do if it is to become the first side to successfully defend its Champions League title.

"I'm happy that I scored in a critical moment of the match, when we were suffering. But above all it was as a team that we got through," Ramos said. "We need to reflect now on things, they dominated for nearly the entire first half. We really suffered. We'll take time now to think about things calmly."

Tuesday's other return fixture in the Round of 16 also ended with the same scoreline as the first leg as Bayern Munich inflicted another 5-1 rout on Arsenal, which collapsed to its heaviest loss at the Emirates Stadium after having captain Laurent Koscielny sent off.

Needing to win by at least two clear goals, Napoli applied the pressure right from the start, with Mertens having a shot deflected over the bar in the opening minute.

Marek Hamsik also fired inches wide, while Lorenzo Insigne had a 30-yard (meter) snapshot turned around the post by Keylor Navas.

Madrid appeared to have weathered the early storm and Gareth Bale threatened but the Spanish side was undone by a moment of brilliance from Napoli. Insigne and Hamsik combined, with the latter threading a delightful pass for Mertens to rush into the area and slot into the bottom right corner.

It was Mertens' 17th goal in his past 16 matches and his fifth in the Champions League this season.

Madrid almost leveled five minutes later when Ronaldo rounded Reina but his attempt came off the near post from a difficult angle.

Napoli also hit the post in the 38th minute as Mertens' diagonal effort crashed off the base of the left upright.

Madrid had scored in its past 46 matches and it leveled six minutes after the break.

Hamsik gave the ball away in the middle of his own half and Elseid Hysaj was forced to head out the danger at the far post, with Ramos nodding in the resulting corner.

"The match changed after their goal. Continuing with that rhythm, that intensity, that drive was impossible because our whole mentality changed," Sarri said. "It removed all hope of qualifying."

Madrid doubled its lead from another corner to all but extinguish Napoli's hopes, before Morata rounded off the scoring.