Barcelona are due to face Chelsea, who eliminated Liverpool, in the semi-finals of the continent's pedigree club competition after brushing aside Bayern Munich.
And Torres expects Guardiola's Primera Liga table toppers and Copa del Rey finalists to knockout the Blues en route to a final with either Arsenal or Manchester United.
If United - who could win a quadruple this season - were to reach the final, Torres also believes Barca would defeat the Premier League leaders.
"Barcelona are clearly the best side in Europe," the former Atletico Madrid forward said in the Daily Mirror.
"United's squad of players is very impressive. You barely notice when they have players out.
"They have footballers like Tevez, Berbatov or Giggs on the bench. But even so I think Barcelona would get the better of them.
"Manchester United suffer an awful lot if they do not control possession.
"Barcelona have much more quality about them and no doubt if the two were to meet, Barca would have the lions-share of possession and that would hurt United."