The Red Devils opened the scoring through Cristiano Ronaldo in the first half, but then had to survive some intense pressure before Wayne Rooney scored the second to practically seal the tie. 

"Yes, [it was] a very good performance," said Ronaldo, speaking on ITV after the game.

"Everyong knows Roma are a good team. It was a tough game, they played very well. But we got some chances and scored, and that was the difference."

Speaking of his own goal - his 36th of the season, he said: "It was a good header, and I feel very happy because I scored and helped the team win.

"We needed to win. Now the next game is at home and we need to win again."

It took some rugged defending, though, and the winger also pointed towards the collective effort, and towards the desire to win the competition. 

"Yes, everyone did their part in this game," he said. "This is good competition, and we really want to win it."

Asked by ITV Sport if he rated their performance as United's best in Europe this season, manager Sir Alex Ferguson hesitated before saying: "Possibly, yes, in view of the quality of the opposition."

He added:  “It’s a very good team we played against of course. We had to defend really well at times.

“We had some lucky breaks in the second half - they could have scored a couple.”

However, Ferguson also admitted: “I should have put Wayne Rooney through the middle quicker. I waited too long,” a reference to the tactical change that reaped almost immediate dividends when Rooney added United's second with another potentially priceless away goal.

Ferguson praised his team's "good, disciplined performance," and stressed: "We didn't lose a goal, which was really vital."

And he summed up the night by saying: “It’s a fantastic scoreline for us and I’m very, very pleased.”

The one concern for United was an injury to Nemanja Vidic, who was substituted in the first half. Ferguson explained: “It’s a knee injury. We’re just praying it’s not anything other than a nerve injury.”

Meanwhile, Cristiano Ronaldo, who scored the opener with a stunning header, claimed United were well worth their victory.

Ronaldo produced a brave, spring-heeled jump to power a Paul Scholes cross down into the net and set United on their way to a commanding first leg lead.

"It's a very good performance. Everyone knows it's a tough game. Roma played very well, but we created a few chances," Ronaldo told ITV1 before leaving the pitch in Rome.

"I think we deserved this win."

It was his 36th goal of a remarkably productive season, and he added: "It's a good header, and I feel very happy because I scored the goal and I helped the team."

Asked about the contribution of the United defence, Ronaldo praised his team-mates. Rio Ferdinand, Nemanja Vidic, Patrice Evra and Wes Brown provided a solid platform and Ronaldo acknowledged this when he said: "Rio, Vid and Pat and everyone played very well."

The Portugal winger now feels United have an excellent opportunity to win the competition.

"I think we have a great chance. The team played fantastic. The team is more mature," he said. "Of course, Manchester United want to win this season."

The first-half was a somewhat cagey affair, with the midfield often over-crowded - but for Manchester United it was a near-perfect 45 minutes. Their defensive solidity ensured a clean-sheet despite some spells of promising Roma pressure, and the prolific Cristiano Ronaldo secured them a precious away goal with a prodigious leap to meet a deftly chipped Paul Scholes cross with a brave towering header.

Roma responded with a period of sustained pressure for the first 20 minutes of the second-half, but United withstood that onslaught and broke to double their lead through Wayne Rooney on 66 minutes.

United manager Sir Alex Ferguson had been able to recall goalkeeper Edwin van der Sar after the Dutchman recovered from a groin strain. And he brought Ji-Sung Park into midfield for Ryan Giggs, with Anderson replacing Carlos Tevez.

Roma were handicapped by the absence of talismanic captain Francesco Totti, who was sidelined with a thigh injury.

It was a nervy start for United as Rio Ferdinand gave the ball away to Mirko Vucinic who played in Mancini before the Red Devils cleared the danger. A long ball intended for Taddei had to be headed to safety by Patrice Evra as Roma looked to exert early pressure on the visitors. Another Roma attack was halted by Anderson's foul on Mancini, but David Pizarro's free-kick was quickly cleared.

United though began to settle and spread the play more. Ronaldo skipped past Mexes but he overran the ball to the delight of the Roma fans, but his side were enjoying some good possession and prepared to be patient.

The Giallorossi broke forward and won a corner off Carrick, with David Pizarro's flag-kick headed just over the bar with some power by Christian Panucci.

At the other end, Ronaldo put Rooney clear on the left, and he played the ball inside to Anderson, who shot woefully high and wide from a decent position some 25 yards out.

Then Ronaldo tried his luck ambitiously with a free-kick from all of 40 yards but it was always drifting wide of goal. United threatened again when Paul Scholes had a shot blocked on the edge of the area from Evra's cut-back, but Roma immediately sprung forward on the counter.

Francesco Totti's deputy, Vucinic, let fly from the edge of the area with a shot that flew just over Edwin van der Sar's bar, before Nemanja Vidic landed awkwardly jumping for a ball with Vucinic and was clearly in trouble. He tried in vain to continue and John O'Shea replaced him, slotting straight into United's defence.

Roma were enjoying good possession at this stage but United were coping well with the high balls the Giallorossi were sending into their penalty area. Pizarro's accurate through-ball nearly put Vucinic in the clear, but Ferdinand's leg made a crucial interception. And a good ball in from the left by Tonetto saw Evra having to head clear at the far post.

But if Roma were scenting a possible breakthrough, they were rocked on 39 minutes when United scored a superb goal. Rooney found  Scholes, whose deft chip was perfectly timed for Ronaldo's storming run and leap, the Portuguese winger heading the ball powerfully down into the net at some cost to his own safety.

He resumed after treatment, having scored seven goals in the Champions League this season, making him the top scorer in this season's competition and answering the critics who still claim he does not deliver in the big games.

Roma might have equalised almost immediately when Vucinic broke into the area and held off Carrick before shooting just wide of the far post from a tight angle.

In first-half stoppage time, United's Anderson was booked for persistent fouling. Then Pizarro was booked for fouling Ronaldo, whose trickery had driven him to frustration.

Roma came out for the second half with greater attacking intent, knowing that to go to Manchester trailing from the first leg would represent a nearly insurmountable mountain. And hey proceeded to pen United back in their own half with sustained pressure on United's defence.

Taddei's cross was headed behind for a corner by Ferdinand, and the corner found its way back out to Pizarro, whose deep cross was followed out by O'Shea before
De Rossi and Vucinic linked up well to set up Tonetto, whose shot flashed narrowly wide of the near post.

Tonetto's mishit cross from the left turned into an unexpected shot that van der Sar had to tip over the bar, with Pizarro's corner deep to Vucinic played back into the middle where Ferdinand cleared the danger. Then Vucinic's long throw was flicked on to Panucci, who volleyed over the bar when he might have done better.

Ronaldo eased the pressure on United with a break forward that Mexes halted  at the expense of a free-kick and a booking. Ronaldo's free-kick was headed over by Carrick before Ferguson responded to Roma's strong start to the second half by taking off Anderson and sending on Hargreaves to bolster the United midfield.

Roma sent on Ludovic Giuly for Taddei, and Giuly was involved immediately, sending in a low cross from the right that van der Sar had to gather cleanly.

Roma's pressure produced a string of corners, from one of which, on 63 minutes, van der Sar was forced to make a superb reaction save from Vucinic's header, Mexes nearly getting to the rebound before United hacked the ball clear.

But with United apparently clinging on, they broke classically to add a second and break Roma's hearts if not their spirit.  The Italian side were guilty of some poor defending as Park helped Ronaldo pass back across goal and Rooney took full advantage of Roma's hesitancy to stab the ball into the net on 67 minutes.

A minute later, goalkeeper made a fine save to turn Ronaldo's 20-yard drive onto the foot of a post and away to safety.

Despite being under pressure for much of the second half, United were now looking threatening on every forward break. Park played in Rooney who cut the ball back for Carrick, whose shot zipped just wide of the post.

Aquilani made way for Esposito before Giuly's strong run down the right ended with him wasting his cross, which drifted over the bar for a goal-kick. Then
Pizarro, with few options available in front of him, shot wide from distance. he stuffing was taken out of Roma by United's second goal.

Carrick delivered a sublime long ball to Ronaldo who in turn found Rooney, but the striker's shot was not of the same quality as the build-up, and went well wide of the goal. Rooney was immediately replaced by Tevez, having put in a splendid evening's work.

Roma: Doni, Cassetti, Mexes, Panucci, Tonetto, De Rossi, Aquilani, Taddei, Pizarro, Mancini, Vucinic. Subs: Curci, Cicinho, Giuly, Antunes, Esposito, Ferrari, Brighi.

Man Utd: Van der Sar, Brown, Ferdinand, Vidic, Evra, Carrick, Scholes, Anderson, Ronaldo, Park, Rooney. Subs: Kuszczak, Hargreaves, Giggs, Pique, O'Shea, Silvestre, Tevez.
Referee: Frank De Bleeckere (Belgium)