Manchester United took a huge step towards the semi-finals of the Champions League after producing the perfect away performance in Rome.

Sir Alex Ferguson’s side were on the back foot for long periods but defended superbly, and came away with a richly-deserved victory courtesy of goals from Cristiano Ronaldo and Wayne Rooney.

Despite having already met twice during the group stages, Roma felt they had a score to settle having bowed out 8-3 on aggregate to United at the same stage of last season’s competition.

The Italians were purposeful in the early stages and could have taken a 16th-minute lead when Christian Panucci outjumped Michael Carrick at a David Pizarro corner only to head over the crossbar.

Mirko Vucinic looked Roma’s best hope of a goal with their influential playmaker Francesco Totti absent through injury and the Montenegro international was just too high with a hooked shot from outside the penalty area on the half hour.

United were dealt what looked like a severe blow when Nemanja Vidic limped off in the first half having twisted a knee after landing awkwardly following an aerial challenge. Resilient as always, the visitors looked unflustered at such hardship, with John O’Shea coming on to partner Rio Ferdinand. Then, six minutes before the break, United snatched the lead with practically their first meaningful attack of the match.

Rooney found Paul Scholes, making his 99th appearance in this competition, on the right edge of the penalty area and the former England international stood up an inviting cross to the back post which Ronaldo, risking serious injury, met at pace with a thumping header which gave Doni, the goalkeeper, no chance.

Roma put United under intense pressure at the start of the second half. First, Max Tonetto fired just wide with Van der Sar rooted to the spot. Alberto Aquilani then saw a cross-shot tipped over the bar by the Edwin van der Sar with some difficulty and finally Wes Brown, asleep at the far post, was caught out by a flick-on from a long throw on the right, gifting Panucci a magnificent opportunity which he wasted, volleying over from nine yards with his left boot.

The game swung on two incidents midway through the second period. A smart header by Vucinic from a left-wing corner necessitated a brilliant reaction save from van der Sar to keep the Romans out. United then went down the other end and made the game safe by snatching a second.

Brown crossed from the right, Park Ji Sung headed back across goal and when Doni spilled the ball it bounced kindly off Rooney’s back, leaving him with the simplest of tap-ins.

Toni made partial amends a minute later by tipping a searing low drive from Ronaldo on to his left-hand post. Carrick, Rooney and Carlos Tevez might have given United an even more flattering victory, but Ferguson will settle for this. United have one foot in the last four, where they are likely to meet Barcelona, who beat Schalke 1-0 away from home.