The teams drew 0-0 in the first leg, United dominating the match but missing a few tempting chances, and the Champions League last-16 tie is finely balanced heading to Old Trafford.
Ferguson rested Cristiano Ronaldo and Dimitar Berbatov for Saturday's FA Cup quarter-final win at Fulham and Carlos Tevez grabbed his opportunity with two goals in another energetic display as United cruised to a 4-0 win.
"It is a very difficult decision for me to make, as I hate leaving great players out," Ferguson told MUTV.
Though spoilt for choice up front, Ferguson has the opposite problem at the back as his long-running centre-back woes continue with Rio Ferdinand and John O'Shea both doubtful.
"Rio is a bit of a concern," Ferguson said. "He's gone over on his ankle and we just have to wait to see how he is now. I just hope he makes it because he is such an important player."
Mourinho's planning was upset when central defenders Marco Materazzi and Nicolas Burdisso suffered leg injuries in the 2-0 league win at Genoa and were ruled out. Defender Cristian Chivu has failed to recover from a thigh injury.
He blasted into English soccer's consciousness with his jig of delight after his Porto team knocked United out at Old Trafford in 2004 and ever since he has been a very irritating thorn in Ferguson's side.
From Porto to Chelsea and now Inter, he has lost only one of 13 matches against the Scot and will not be remotely fazed by United's record run of 20 unbeaten Champions League matches.
Midfielder Sulley Muntari, who scored a penalty at Old Trafford last season when Portsmouth beat United 1-0 in the FA Cup, is also due to return to Inter's starting lineup.
