MUNICH - Arsene Wenger's future was plunged into further doubt on Wednesday as Thiago Alcantara inspired Bayern Munich to a 5-1 rout of hapless Arsenal to leave the Gunners facing a seventh straight Champions League last-16 exit.

Bayern extended their Champions League record to 16 straight home wins by flooring the Gunners with three goals in ten second-half minutes. Bayern knocked Arsenal out at the same stage in 2005, 2013 and 2014 and look comfortably placed to make it four times after romping through Wednesday's first leg. The Allianz Arena defeat raises the pressure on Wenger for the return leg on March 7 with only Alexis Sanchez's away goal for comfort. The result matched the 5-1 group-stage thrashing Arsenal received in Munich in November 2015 -- the club's joint record away defeat in Europe. Arjen Robben's superb curling shot gave Bayern the lead on 11 minutes, but Sanchez levelled by drilling home after Manuel Neuer saved his penalty on 30 minutes. Robben also admitted he was surprised by the big win.

Bayern hit top gear after the break with a flurry of goals in quick succession. Robert Lewandowski headed Bayern back into the lead on 53 minutes before Thiago added two in quick succession while Thomas Mueller came off the bench to complete the rout . Bayern spent the opening minutes camped in the Arsenal half and took the lead on 10 minutes through Robben's wonderful strike.

The Dutch winger cut in from the right and curled home a superbly-weighted shot off his left foot from outside the area. Arsenal then raised the tempo and started pressing the hosts. Bayern defender Mats Hummels was given a yellow card for fouling Sanchez just outside the box. Mesut Ozil drilled the resulting free-kick at Neuer, but moments later Arsenal were awarded a penalty. Lewandowski mistimed a clearance in the area and struck Laurent Koscielny's raised leg.

Despite Bayern 's furious protests, Serbian referee Milorad Mazic pointed to the spot. Neuer saved Sanchez's penalty, but the Chile international drilled home the rebound at the second attempt. It was the valuable away goal Bayern had talked about not conceding in the match's build-up.

There were equally furious Bayern protests at the other end when David Alaba's cross struck Hector Bellerin on the hand , but the referee waved play on. It was 1-1 at the break, but Bayern stepped up the pressure in the second half. Robben released Philipp Lahm who put in a perfect cross and Lewandowski twisted to tuck his header past David Ospina's reach.

The Poland hot-shot then flicked Xabi Alonso's pass into Thiago 's path and the former Barcelona midfielder fired past Ospina. Lewandowski hit the crossbar on 61 minutes, but Thiago added his second when his shot from the edge of the box deflected past the Arsenal goalkeeper on 63 minutes. Mueller came on for Lewandowski on 86 minutes and added Bayern 's fifth two minutes later after Thiago squared the final pass.

Meanwhile, Real Madrid shrugged off conceding an early away goal to take a huge step towards a seventh straight Champions League quarter-final as goals from Karim Benzema, Toni Kroos and Casemiro sealed a 3-1 win over Napoli on Wednesday. Lorenzo Insigne's stunning 40-yard strike had the travelling hordes in dream land after just eight minutes of the last 16 first leg. However, Benzema soon headed home an equaliser before Kroos and Casemiro fired home from outside the box early in the second half to give the holders a commanding lead ahead of the second leg on March 7.

With former Napoli great Diego Maradona watching on, the atmosphere reached fever pitch before kick-off as up to 10,000 travelling fans were estimated to have made the trip from Naples for only their side's second ever appearance in the last 16.

By contrast, Real are in the knockout stages for the 20th straight season and it was the home fans who nearly had something to cheer inside 30 seconds as Benzema's shot from close range was parried by Pepe Reina. However, it was Napoli who got off to the perfect start just eight minutes in when Insigne took aim from 40 yards and caught Madrid 'keeper Keylor Navas out of position with a superb effort that curled around the Costa Rica international.

Madrid, though, showed the response of champions to level just 10 minutes later when Dani Carvajal's cross with the outside of his right boot picked out Benzema to power home a header from close range. Cristiano Ronaldo should have had one of the two goals he needs to reach 100 in European competition on 27 minutes when great work from Benzema and Luka Modric freed the World Player of the Year inside the area, but he blasted well over the bar.

Madrid's control of the first 45 minutes grew as the half went on and only a combination of Reina and the post denied the hosts a lead at the break. This time Ronaldo was inch-perfect with his low cross for Benzema, but his effort was tipped onto the woodwork and behind by Reina.

The tie did swing decisively in Madrid's favour within 10 minutes of the restart however. Firstly, Ronaldo played provider once more with a fine run down the right and measured cut-back for Kroos to slot home from the edge of the box. Then Napoli were struck by a thunderbolt from the most unlikely source as defensive midfielder Casemiro pounced on a looping clearance to volley first-time past a helpless Reina.

Napoli had the chances to set up a thrilling return leg as Dries Mertens, who had scored 14 goals in his previous 11 appearances, fired over with the goal at his mercy from former Madrid winger Jose Maria Callejon's fine lay-off. Mertens also saw another effort smothered by Navas from close range and Callejon a goal ruled out for offside as Napoli slumped to their first defeat in 19 games.