The pair are good friends and Verratti was famously in tears at Ibra's farewell ceremony at the end of last season.
Verratti told Telegraph: "Zlatan was a player who was very important for the club and he has done a lot to build up PSG worldwide and if we won a lot, we should thank him.
"Ibrahimovic's debut? I'm not surprised at all. He is Ibra. He deserves a start like that. You can see he is very focused. He is a great player and I think he will continue to do very well.
"When I played with Ibrahimovic, we talked a lot. We both wanted to win. The best thing was to watch him train. He really wanted it and when he was off the field, he did not smile much. He has a winning mentality."