Messi struck five goals in their 7-1 Champions League rout of Bayer Leverkusen last night.
"The circumstances don't matter, he competes against himself. We only try to provide the conditions so that he can receive [the ball] as many times as possible where he feels comfortable [on the pitch]," said Guardiola.
"It's not easy to score five goals in a game. We are very fortunate to have a player like this, we can only enjoy him and this team.
"The throne is his, only he will decide when to leave it."