In Melbourne, they led the top seeds by a set only to lose in a thrilling three-setter, but in the California desert, they allowed the Czechs no such comeback.
Despite a shaky start for Sabalenka on serve, as she served four double faults in her first two service games, the duo won the last three games of the first set from 3-3, and the last four from 2-2 in the second set, to seal their first triumph.
The unseeded duo was clutch on the biggest points in the second set, saving all six break points they faced and serving four combined aces.
“I think that we were playing quick and don’t really give opponents time to do anything,” Sabalenka said.
“In Australian Open, it was learning each other. And now we are, like, ‘Okay, so she’s doing this. I’m doing this,’ so we are good.”
Added Mertens: “I think we don’t make really easy mistakes, especially serving and returning was very important because in the rally, they can do a lot of things. They can come to the net, go with the volleys. I think we really played aggressive, those two shots.”