The sixth seeded defending champions lost the closely fought final 4-6 6-7 (5) to the third seed Dutch-Romanian combination in one hour and 11 minutes.
It was crucial for Bopanna to win since he was defending 1000 points here. He is striving to re-enter top-10 in the run up to Rio Olympic Games so that he can get a direct entry into the prestigious event.
There was little to separate the two pairs in the tight contest. Bopanna and Mergea got only one breakpoint in the opening set which they could not convert while Jean-Julien Roger and Horia Tecau did not miss the one break-opportunity they got.
Another Indian tennis star Sania Mirza had also lost the women's doubles final with partner Martina Hingis, yesterday.