Chief Sports Writer Scott Wilson previews this evening's two Champions League quarter-final second-leg ties.

Manchester United (1) vs Chelsea (0)

Wayne Rooney's first-leg winner at Stamford Bridge has put Manchester United firmly in the driving seat ahead of this evening's decider at Old Trafford.

The striker will be back in the starting line-up after missing United's weekend win over Fulham through suspension, and centre-half Rio Ferdinand should also be available.

United are on a 27-game unbeaten run at home, and while their last defeat at Old Trafford came at the hands of Chelsea last April, it is hard to see Sir Alex Ferguson's side slipping up in such a high-profile fixture.

Chelsea will have to offer more of an attacking threat than they mustered last Wednesday, and it will be interesting to see if Carlo Ancelotti continues to back the misfiring Fernando Torres.

The Spaniard was only a substitute in the weekend win over Wigan, and there must be a temptation to pair Didier Drogba with Nicolas Anelka.

However, Torres is one of the few players to have mastered Nemanja Vidic in the past, and Chelsea's Champions League hopes could ultimately rest on his shoulders.

Shakhtar Donetsk (1) vs Barcelona (5)

After crashing to a 5-1 defeat in the Nou Camp, Shakhtar Donetsk will have to produce one of the greatest European comebacks of all time if they are to progress to the last four.

As if last week's first-leg defeat was not enough, the Ukrainians suffered a 1-0 home defeat to Obolon Kiev at the weekend, a result that ended a 56-match unbeaten home run in all competitions.

It would be no surprise to see Barcelona make it two home defeats in four days, especially as Shakhtar will be without the injured Darijo Srna.

Barcelona boss Pep Guardiola insists his side will not be resting on their laurels this evening, but with a Copa Del Rey final against Real Madrid on the horizon, he could decide to make changes.

Bojan Krkic would probably have started had he not torn his knee ligaments in the weekend win over Almeria, while the inspirational Andres Iniesta is suspended.

However, with David Villa and Lionel Messi both expected to be involved, Barcelona should cruise into the last four.