The Uruguay striker spent three seasons with the Chilean manager at Villarreal from 2004-07 and excelled under his tutelage, topping the La Liga scoring chart in 2004/05.
Former Real Madrid boss Pellegrini arrives at the Etihad Stadium on a three-year deal after leading Champions League debutants Malaga to the quarter-finals last season.
Speaking in the August 2013 issue of FourFourTwo, out now, regular columnist Forlan labels the 59-year-old as "good tactically" and a "calm, intelligent figure."
He says: "Pellegrini is a great manager and a great person. He's an intelligent man who had a life before football and still has one away from it. He obsesses about football when he's at work, but then he goes home and has other interests. He's a cultured man.
"Pellegrini is good tactically and his teams pass and attack with the ball on the ground. He knows how football works. He's moving to a country where they let you work; he'll have pressure, but not the internal battles he had at Madrid. Honestly, I think he'll be a success."
The 2011/12 Premier League champions have already been active in the transfer market as they bid to regain the title they lost to city rivals Manchester United last term, spending £45 million on Fernandinho and Jesus Navas.
Keeping a large squad of talented players content throughout the season is no easy task, but Forlan insists one of Pellegrini's strengths is to treat each of his players fairly.
"It's impossible to keep every player happy, but everyone considered him fair [at Villarreal] and knew he'd tell them the truth if he didn't select them. Not every player liked what they heard, but he was usually right."
Read Diego Forlan's latest column in the August 2013 issue of FourFourTwo digitally, via the App Store and in print. The issue features an exclusive interview with Manchester City's £30 million midfielder Fernandinho and an in-depth account of David Moyes as he prepares for life as the new Manchester United manager.
The magazine also looks at the Brits who played in the Bundesliga as well as talking to Joe Royle and Marseille's French international Mathieu Valbuena. Subscribe now!
