Kompany is back in first team contention having had an eight-week lay-off for a knee problem he sustained against Crystal Palace in November.
That was the Belgium centre-back's 35th injury since joining the Premier League club from Hamburg in 2008.
Now, at the age of 30, Kompany's long-term fitness and durability is uncertain and even his City manager has no idea whether the defender will recapture the dominant displays that made him such a key player.
"I don't know, it is a good question. It is not the first time we have talked about that," Guardiola said when asked about Kompany's future on Friday.
"The good news is he is back and hopefully he stays fit for a long time because then we will see what level he is at.
"When he is fit, he is at the top level, we cannot deny how good Vincent is, but to achieve that maybe he needs a bit of time.
"Everybody needs that when you have been out for a long time. Mentally he is strong, he knows what he needs to do, but what I would like is for him not to put a lot of pressure on himself.
"He needs weeks and weeks and weeks of training sessions and to just go out there and play the games.
"He doesn't have to put pressure on himself to do amazing things, he just has to do the simple things and be the defender he was.
"He just needs to keep it simple and do the things he had always done. Once he is back up and running, he will achieve the things he wants, he will get back to his level."
Kompany has repeatedly claimed that he feels he can regain his full fitness and enjoy an uninterrupted run in the first team.
But Guardiola revealed that he has spoken with the player and warned him to take his comeback in a steady and sustainable manner.
"Yes, his mentality is that he feels he wants to come back immediately," Guardiola said.
"He wants to be perfect immediately, but I know, in this business, you do not get time.
"You are judged immediately, but he has to feel his way. His manager and his teammates will give him time to come back, he has been away for a long, long time."
Guardiola must name his Champions League squad for the knock-out stages in two weeks and the Spaniard admitted he must make a decision on whether to risk naming Kompany to one of the places.
"I haven't thought about the Champions League squad yet," he said.
"He was on the list for the first half of the season, but unfortunately he was injured and could not play.
"We are going to see which players are going to be involved, everybody has a chance. Hopefully, he is able to play (in the Champions League) in the second half of the season."
One player whose City career is currently being delayed is the Brazilian forward Gabriel Jesus who has not completed the paperwork over his January transfer to Eastlands.
Although Jesus's move was initially agreed last year, Guardiola confirmed the administration process is delaying the highly-rated 19-year-old's debut.
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