However Granollers has been struggling with injuries of late and the pair hasn't played together since Wimbledon. But they beat Koolhof and his former partner Matwe Middlekoop in the final of Rotterdam in February 6-1, 6-3 and have been consistently one of the best teams in the world.
Sitak said they would watch that match on Youtube in preparation for their encounter.
"It's not the best draw obviously because they are seeded number six." Sitak said.
"But it's ok because we knew we would probably face a seeded team in the first or second round. Our goal is to go deep in the slams and to do that you have to beat the top teams, and we have to play them first round which is fine."
Sitak and Koolhof have only played four tournaments together but the Kiwi says they have gelled quickly.
"We are very happy with the four weeks together and made one ATP final in Atlanta. I felt Wes is the kind of partner I wanted to have." Sitak said.
The move away from Super tie breaks and no advantage at deuce in ATP tournaments to full sets in Grand Slams is something that Sitak relishes.
"We are ready for a long match and are both fit, at Grand Slams there are no super tie breaks, and we play full sets with advantages so in my opinion the better teams win."