United leave Roma reeling
Ronaldo and Rooney score to take control of tie
Manchester United are in a commanding position to qualify for the semi-finals of the UEFA Champions League after a 2-0 win over Roma at the Stadio Olimpico.
Cristiano Ronaldo and Wayne Rooney grabbed the goals for the Premier League leaders to give Roma a mountain to climb in the second leg at Old Trafford next week.
After losing Nemanja Vidic to injury after half-an-hour, United took the lead six minutes before half-time when Ronaldo rose powerfully to meet Paul Scholes' cross for his 36th goal of the season.
Roma responded positively after the break with Christian Panucci firing over when unmarked and Mirko Vucinic forcing a fine reaction save from Edwin van der Sar.
But United took a giant stride towards a semi-final date with Barcelona or Schalke when Rooney pounced on a mistake on 66 minutes to score from close range.
Park Ji-Sung's inclusion in the United side at the expense of captain Ryan Giggs was a surprise and he got into a good position after 12 minutes only for Panucci to take the ball off his toes as he shaped to shoot.
Roma hit back and Vucinic should have tried his luck on goal, but opted instead to pass to Alberto Aquilani and the move broke down.
This was a good spell for the home side and Mancini saw his effort deflected to safety by Vidic before Panucci headed over the top from Rodrigo Taddei's corner.
Play broke down the other end and Rooney released Anderson, but the Brazilian, who has yet to score for the club, blazed a shot over the bar.
Roma carved out a good chance in the 28th minute when Vucinic escaped his marker and cut inside, only to rattle a shot over the top.
Vidic needed treatment after landing badly following an aerial challenge with Vucinic, with the Serbian replaced by John O'Shea after twisting his knee.
United gained the advantage on 39 minutes when Rooney released Scholes on the right and he delivered a delicate chip into the area.
Ronaldo ran from deep and headed the ball beyond Brazilian goalkeeper Doni and, although the Portugal winger was left dazed in the incident, he recovered quickly to United's relief.
Roma could have equalised three minutes later, but Vucinic dragged his shot wide of the post, while they started the second half brightly as Max Tonetto sent his effort off target.
The hosts kept up the pressure and Panucci squandered a good chance in the 52nd minute when he was left free at the back post, but only succeeded in sending his effort over the top.
Roma responded and substitute Ludovic Giuly got clear down the right only to send a poor cross into the grateful arms of Van der Sar.
However, Van der Sar needed to look alert to make a fine one-handed save from Vucinic's near-post header from a corner.
This was a difficult time for United and Vucinic was proving to be a bit of a handful in the absence of the injured Francesco Totti.
United, however, made it 2-0 in the 66th minute when Park kept the attack alive when he headed the ball into the six-yard box at the back post.
Roma keeper Doni flapped at the ball and it fell kindly for Rooney to prod home under pressure from a defender.
Ronaldo then skipped away from his marker to fire in a low shot from 25 yards which Doni turned on to a post.
With a two-goal cushion, United were knocking the ball around well and Michael Carrick came close in the 71st minute, his effort going narrowly wide.
Rooney had put in a hard shift and was replaced by Carlos Tevez with six minutes remaining as Roma looked dispirited.
Tevez saw his effort go wide before Ronaldo rattled a superb volley narrowly over the bar as United finished the match in style.