Three days can be a long time in football as Nicklas Bendtner proved on Tuesday.

On Saturday against Burnley the gangly Dane's finishing prowess was distinctly Sunday morning pub league standard but on Tuesday it was worthy of the Champions League as his first Arsenal hat-trick helped power his side into the quarter-finals.

Bendtner, an industrial presence in a team full of artists, divides opinion at The Emirates like no other.

Willing worker though he is, he can on occasions look a little out of step with the silky movements of those around him.

He is an easy target for fans' when things are not going well but manager Arsene Wenger has always stood by him since spotting him playing for FC Copenhagen.

"It shows you how football can change very quickly," Wenger said of Bendtner.

"It can go quickly up and quickly down. It shows that he had not lost his confidence and he came back with a good focus and belief, that's one of his strengths, his confidence levels remain relatively stable.

"He has the size and presence that we need because we are normally a very short team and he helps us offensively and defensively," he added.

While Bendtner grabbed the match ball with two routine finishes and a stoppage time penalty, Wenger was quick to praise the impact of Samir Nasri and Andrei Arshavin whose pace and trickery tore Porto to pieces on the slick Emirates carpet.

Such was their impact that the absence of captain Cesc Fabregas went almost unnoticed while Nasri's exquisite solo dribble for Arsenal's third goal was sheer class.

"Nasri is developing very well," Wenger said.

"What he showed tonight he shows in training and we expected that to come out in the games.

"He is a player with talent and he showed that tonight like he did on Saturday and he has started to be efficient now. Tonight he made the first goal and scored a great goal. Great players assist and score goals," Wenger added.

Arjen Robben's strike sent Bayern Munich through to the Champions League quarter-finals on away goals, despite a 3-2 defeat by Fiorentina in a thrilling last 16 second leg.

The Dutchman found the net from 25-metres with a wind-assisted shot in the 65th minute to make the aggregate score 4-4 after the four-times European champions won the first leg 2-1.

Fiorentina's Juan Manuel Vargas took advantage of a Hans-Joerg Butt fumble for the opener in the 28th minute and Stevan Jovetic made it 2-0 for the hosts in the 54th before the home crowd went on an emotional rollercoaster ride that ended in disappointment.

Mark van Bommel levelled the tie for Bayern in the 60th before Jovetic bagged his second, only for Robben to decide it with his splendid strike almost immediately after.

"It was a tough match, especially because of the conditions," Bayern midfielder Sebastian Schweinsteiger told Sky Italia.

"We were clever to keep the ball on the ground. At the end of two legs we have shown ourselves to be stronger," he added.

Coach Cesare Prandelli said he was bitter that an offside goal in the first leg of Fiorentina's Champions League tie against Bayern Munich had ultimately cost his side a place in the quarter-finals.

"We are talking about being knocked out by a goal that was offside by two metres," Prandelli told a news conference.

"I'm bitter," he added.

Prandelli was proud of the way his men had acquitted themselves in European club football's premier competition this season, after they beat Liverpool twice on the way to winning five out of six of their group stage games.

"Given the spirit we have taken on the big teams with, we go out with our heads held high," he said.

"When a team loses in this way you must feel proud of what you've done and what you're doing. Winning six games out of eight is not something everyone can do.

"The lads worked and interpreted the game as we had prepared, so my work was more than satisfying," he added.