MANCHESTER: Real Madrid and Bayern Munich have one foot in the Champions League last four as they go into this week's quarter-final second legs while Barcelona face a harder fight for their berth with doubts over the availability of injured Lionel Messi.

With Real holding a comfortable 3-0 lead over Galatasaray before Tuesday's trip to Istanbul and Bayern travelling to Juventus with a 2-0 advantage on Wednesday, two semi-final spots seem already taken.

The other ties are much more delicately balanced with competition favourites Barca locked at 2-2 before hosting Paris St Germain on Wednesday and Borussia Dortmund tied at 0-0 before entertaining debutants Malaga on Tuesday.

The goals and magic of World Player of the Year Messi would usually be enough to dig Barca out of any sticky situation - as they did against AC Milan in the previous round - but if the Argentine does not play the team will need a different approach.

Messi sat out Saturday's 5-0 win at home to Real Mallorca in La Liga with a hamstring problem, the first league game he has missed through injury since the 2010-11 season.

He had physiotherapy and did some fitness work on Sunday but it was unclear whether he would be fit to face PSG.

Barca, though, still have reason for optimism that they can reach a sixth successive Champions League semi-final as Messi's stand-in against Mallorca, Cesc Fabregas, netted a hat-trick and coach Tito Vilanova was back on the bench after cancer treatment.

They are in good spirits after the return to competitive action of defender Eric Abidal following a liver transplant, while they remain 13 points clear of Real at the top of La Liga and have not lost at home in Europe for more than three years.