Robert Lewandowski scored twice on Tuesday as Bayern Munich powered into the Champions League semi-finals for the fourth year in succession with a 6-1 second-leg routing of ten-man Porto.

Needing to overturn a two-goal deficit after last Wednesday’s shock 3-1 first-leg defeat at Porto, Bayern produced a devastating first-half display to claim five goals and eventually won the tie 7-4 on aggregate.

“It couldn’t have gone better,” beamed goal-scorer Thomas Mueller.

“Sometimes it’s fun to play with your backs against the wall.

“We all had hopes, but no one expected that.”

Lewandowski now has 22 goals in all competitions while Mueller, Jerome Boateng and Thiago Alcantara also grabbed first-half goals.

“Many people thought we couldn’t do it, but we are FC Bayern Munich,” said Lewandowski.

“We knew we had to step on the gas, but to go five goals up at half-time is really crazy.”

The game’s tempo dropped after the break allowing Porto captain Jackson Martinez to score a consolation goal.

Porto finished with ten men when defender Ivan Marcano received a second yellow card just before Xabi Alonso crashed home a free-kick — their coach Julen Lopetegui was also sent from the touchline.

“The first half here in Munich cost us everything, we were punished and now we have to pick ourselves up again,” said Lopetegui.

The scoreline matches Porto’s record away defeat in Europe when they lost 6-1 at AEK Athens in the defunct European Champion Clubs’ Cup in 1978.

Having routed AS Roma 7-1 away in the group stages and mauled Shakhtar Donestk 7-0 in Munich in the last 16, Bayern produced more clinical finishing in the first-half.

The Germans kept alive the dream of repeating their 2013 treble of Champions League, Bundesliga and German Cup crowns by going into Friday’s semi-finals draw.

They can pick up their first silverware of the season on Saturday if they beat Hertha Berlin at home to have the Bundesliga title confirmed for a third year running.

The victory was all the more impressive as it came without injured star wingers Franck Ribery and Arjen Robben, while Germany captain Bastian Schweinsteiger stayed on the bench.

Bayern attacked from the outset, enjoying 75 percent possession early on, and rarely allowed Porto into their half.

Lewandowski hit the woodwork with nine minutes gone and the opening goal came just five minutes later.

Spain defender Juan Bernat, a constant threat on Bayern’s left wing, swung in a corner and Thiago, who scored their away goal at Porto, headed home at the near post.

The crucial second goal came from Bayern’s centre-backs as Holger Badstuber, in for Dante in the only change from the side who lost at Porto, headed on a corner and Boateng powered the ball home on 21 minutes.

Lewandowski compounded Porto’s misery as Philipp Lahm’s cross from the right was flicked on by Mueller and the Polish striker was on hand to power home his header.

With Bayern scoring at will, Fabiano was wrong-footed when Mueller’s strike on 36 minutes took a deflection as the hosts went 4-0 up.

Lewandowski added his second five minutes before the break to make it 5-0 with 50 minutes still to play.

Mueller passed off to the Polish striker, who took a couple of touches to create space, then drilled the ball low into the corner.

With the game effectively over as a contest, Martinez gave Porto some late hope when substitute Evandro’s cross was headed home from close range on 73 minutes.

Marcano’s foul on Thiago led to the free-kick which Alonso drilled home on 88 minutes to cap Bayern’s rousing night.

The the exitement got to their coach Pep Guardiola who ended up splitting his trousers while screaming sideline instructions.