Sir Alex Ferguson has urged Manchester United to go ''full throttle'' in their attempt to overcome FC Porto at Old Trafford.
Although the Portuguese outfit, led by Jose Mourinho, overcame United at the first knock-out stage in 2004, few are expecting a repeat, with Ferguson's men odds-on favourites to reach their third successive semi-final.
But the Red Devils chief is taking nothing for granted after beating Mourinho's Inter Milan in the last round. And even though his side are back in action barely 48 hours after the thrilling 3-2 win over Aston Villa, he is demanding that they hold nothing back.
''It would be stupid to think this is going to be easy,'' said Ferguson. ''When teams are used to winning their domestic title, as Porto are in Portugal, you always feel they will play with great confidence.
''They have a lot of South Americans in their team as well, which gives them a great physical strength.
''By beating Atletico Madrid in the last round, Porto proved they will be hard to beat. Complacency does not come into it as far as we are concerned.
''We will be going at full throttle in order to get the result we want.''
As well as that trio, Ferguson is likely to call on Park Ji-Sung, whose energy could be a useful weapon.
Meanwhile, Porto coach Jesualdo Ferreira could not have been more delighted when his side drew Manchester United in the Champions League quarter-finals.
"It was always likely we would be drawn against an English side," said the 62-year-old. "Of seven possible opponents, four were English. But Manchester United were the ones I would have chosen to play against and my players would have made the same choice.
"It is a chance to prove what we can do against a top team. I have watched United and know what to expect. We will be well prepared."
However, Ferreira does recognise the financial gulf that exists between the two sides, with United counterpart Sir Alex Ferguson able to construct a massive squad that is beyond his capabilities.
But there is no sense of inferiority in the Porto camp, just a determination to work smarter in an effort to bridge the gap.
"When you look at the money rankings and analyse the differences, it gives a certain pleasure to see us there," said Ferreira. "United and Porto's conditions are different. The leagues are different and the players too.
"I would like to say we could sign big stars but it wouldn't be true. We have to sign players nobody knows. But the game is the same and we can compete for results and titles. We just have to be cleverer than the other teams."
Ferreira will be counting on the formidable striking talents of Hulk and Lisandro Lopez to get the away goal Porto crave. But he will be relying on the same players that have been the basis of Porto's charge to the top of the table as they look to emulate Mourinho's team by reaching the semi-finals.
"It is hard for us to save players," he said. "We have a heavy schedule but have not been able to rest players because they are all games we want to win. It is inevitable we have so many games but we just have to cope with it."