The Giallorossi return to Old Trafford - the scene of the last season's 7-1 humiliation - tonight looking to overturn a 2-0 quarter-final first-leg defeat.

The Romans have sought to put the memories of their heaviest European loss firmly behind them and, having beaten Real Madrid home and away, were among the favourites for this year's competition.

Their campaign though stumbled last week in the Stadio Olimpico and Spalletti knows his side now have their work cut out.

But the Roma boss is refusing to write off his side's chances of progressing just yet.

"It's an underlying theme in football that nothing is impossible," he said. "So who knows what will happen tomorrow.

"We have to play the first 60 minutes almost as if the first leg never happened - we can't think of that result.

"After 60 minutes we'll see how we stand but if we go all out from the beginning that would be very counter-productive, especially against a team with Manchester United's attacking potential."

He added: "We have to be really good given the score in the first leg. It will be a huge task, but we'll try our best and I believe we can do it.

"We have to wait for our moment, create chances and we need to take them. And I think we will."

Roma's hopes of reaching the semi-finals are further hampered by the absence through injury of talismanic skipper and chief goal threat Francesco Totti.

Matteo Ferrari joins him on the sidelines after undergoing a knee operation on Friday which rules him out of action for 20 days.

Spalletti is aware just how big a blow the duo's loss is, but insists his team have enough strength in depth to still win the tie.

"Our strengths lie in playing as a group," he continued. "We have a lot of confidence and a lot of scorers and we have to keep this in mind tomorrow and play to our strengths as a group. I believe our players are capable of winning.

"I don't want to say we'll do it because that would be very presumptuous of me and it could even provoke United.

"We have to be humble, work hard, give everything and play our game. But I know the players very well and they are always capable of fighting. We want to be here and we are here and we are going to play to qualify for the next round."

Knowing that his side need to score at least three goals to reach the semi-finals Spalletti is expected to go with an attacking 4-2-3-1 formation, with Rodrigo Taddei, Simone Perrotta and Mancini pushing up to support Mirko Vucinic.

Perrotta should return to the starting line-up after missing the first leg through suspension, as should Juan who was injured for the Stadio Olimpico clash.

Roma have been boosted by Alberto Aquilani's earlier than expected return from injury, although how much of the game the midfielder plays will depend on a late fitness check.