Manchester United boss Sir Alex Ferguson admits Cristiano Ronaldo's winner at Porto was critical to their Treble hopes.

In his match programme notes for their victory over Portsmouth, Ferguson wrote: "There'd been a great deal of negative feeling for our chances in Porto, with much emphasis on no English team having won there before. In the event we won well, with a performance that will be remembered of course for Cristiano Ronaldo's stunning goal. Hit from 40 yards at rocket pace it got everybody talking - including, I might say, his own team-mates!

"Of course we were also helped by the return to action again of our centre-back pairing of Rio Ferdinand and Nemanja Vidic, giving us the understanding, balance and stability in the back line that served us so well in the first half of the season. But at the end of the day, I felt it was the freshness that was there right through the team that enabled us to account for a very strong side and win a pivotal game. It was a key result for us, not just in terms of the Champions League, but to maintain a momentum that I hope will make us successful in the other competitions."