PSG boss Thomas Tuchel introduced Mbappe at half-time in Brittany, with Nolan Roux's goal having put Guingamp ahead.
The change immediately paid dividends - Mbappe combining with Neymar who drew a foul from Jordan Ikoko, and the Brazil forward duly levelled from the spot.
And Mbappe would have the final say with two exceptional finishes late on to secure the win, but the World Cup winner insists he is still playing second fiddle to Neymar.
"Neymar is a superstar, much more of star than me," he said in his post-match interview on the pitch.
"I am not at that level yet. He has worked many years at Barca to prove that and we have many players in this squad who are superstars.
"I don't think I changed everything, the whole team wanted to do better than in the first half. In the second half the team showed a whole new face. With the two goals I helped the team but that was not just down to me."
However, Mbappe says that triumph is now behind him, and he is already focusing on the next challenge.
"We celebrated like we should do, but football continues," Mbappe continued.
"My career is just starting and I have big ambitions whenever with the club or national team. You can't sit around and do nothing, you have to carry on."