The 'Red Devils', which started as a clear favorite at the junction with the Portuguese champions, are now in a delicate situation.
Alex Ferguson of pupils are required to check at the Dragon. In addition, it will surely win, unless the match 2-2 to play longer, or push for more goals, in which case seal their ticket to the semifinals by many more marked in stage rival.
The psychological advantage is now for Oporto, to recall that in 2004 eliminated Manchester United in the second round of the Champions League champions and finished with a machine that glowed on the lawn Deco and José Mourinho was the bench.
Among the great offensive of the Portuguese duo is formed by the Argentine Lisandro Lopez and Brazilian Givanildo Vieira de Souza 'Hulk', assisted by another of the figures of the team, also Argentinian Lucho Gonzalez.
"We can look in the eyes and play as equals," Hulk told. His partner Lopez is also the third top scorer of the current Champions League, with six so.
However, the Oporto's weakness could be the defensive side, where it is capable of big mistakes in important moments, such as those committed by the Brazilian goalkeeper Helton at Atletico Madrid in the round or Bruno Alves in the first leg in Manchester.
Manchester United is also engaged in a tough battle in the Premier League, which leads to Liverpool and has just one point, and Chelsea (3) to four.
In recent weeks, the 'savior' of the English champion, European and world has been the Italian Federico Machede couple, both of which marked the victory before the Aston Villa (3-2) and Sunderland (2-1), the it confirms one of the great promise of European football.
The stars of Old Trafford club does not seem to scare Oporto, grown after recent results. "Cristiano Ronaldo as I defend against any other opponent is like the others," said the young French of Senegalese origin Aly Cissokho.
Manchester United had signed so far, a good record in the competition, surpassing the group of the first round next to Villarreal, ahead of the Danish Aalborg Glasgow Celtic and Scots. Eighth, had left out the Italian champions, Inter Milan.
With the grand finale of Rome on the horizon, both sets a promise attractive clash for a place in the penultimate round, where the winner will be with Arsenal or Villarreal, who also play on Wednesday.