The two managers will go head-to-head in the Manchester derbies during the 2016/2017 season, and the Netherlands international expects a fascinating duel between the two men.
In a recent interview with Goal.com, the 32-year-old Netherlands captain, who has worked under both Guardiola and Mourinho, shared his opinions on their rivalry in the English Premier League.
"They are both big coaches.
"I worked with each of them for three years. They are top professionals, and they will bring their own style of play and mentality to the team. I'm convinced of that.
"It will be interesting to follow. But it's not only about Pep vs. Mou, but also about the players on the pitch in the end. But I'm sure you will notice their handwriting."
When asked about which boss he prefers to play under, the former Chelsea man refused to reveal his answer.
"No, I cannot say that, they were two completely different periods in my career.
"When I worked with Mourinho I was still young and it was my first club abroad. With Pep, I was already older and it was different. Both have been interesting and suited me in my career."
During his three-year spell at Stamford Bridge, Robben won two Premier League trophies under Mourinho before he made his switch to German giants Bayern Munich in 2009. Since his arrival to Allianz Arena, he has clinched four consecutive Bundesliga titles, and three of those came during Guardiola's time at the club.
