At the end of January, Sane suffered ankle ligament damage during the club's FA Cup tie at Cardiff City, and Guardiola claimed that the winger would not return until March.
However, the Germany international is in contention to feature in the squad for Tuesday's Champions League contest with Basel and while the player still has work to do, Guardiola has admitted that he has been left delighted by his early comeback.
At a press conference, the 47-year-old told reporters: "I am surprised, but he has worked a lot. I couldn't expect it with a young guy, to be so professional.
"He is not in perfect condition, but he has run a lot and wants to help us. It is not perfect, but he is with us, and that is good news. They have done a good job, both the physios and Leroy himself."
Sane has scored 11 goals in 33 appearances in all competitions this season.