The Dutchman, who has been the driving force behind the Bundesliga leader's chase of three titles, even scored an almost identical goal to Messi, chipping the ball while at full speed over the Hanover keeper for Bayern's second of the afternoon.
Barcelona's Messi had done it against Arsenal in the Champions League quarter-finals earlier this month when he netted all four of his team's goals.
"Of course Messi is better," Robben, who has scored 14 league goals this season, told Sky Television.
"I can only improve. There are other great players like Cristiano Ronaldo and Didier Drogba but Messi is up there alone. He is just in a class of his own," he said with a smile.
Robben has not been less spectacular though since joining Bayern in the summer from Real Madrid, steering the Germans to the Champions League last four with stunning goals, including an eye-popping volley against Manchester United in the quarter-finals. Bayern are also in the German Cup final.
Hanover coach Mirko Slomka said: "It is just an amazing quality. No matter how many videos you watch to prepare for him, when he plays like that, it just does not matter."
Robben insisted all his performance did was to prepare his team well for the first leg of their Champions League semi-finals against Olympique Lyon on Wednesday.
"It gives us confidence because it was the first game in our final stretch of games in this season and it was a good beginning. But Wednesday is a completely different game," the 26 year-old said.
Should they advance he could be in for a meeting with Messi, whose Barcelona face Inter Milan in the other semi-final.
