MELBOURNE, Australia — Third-seeded Coco Gauff had some familiar struggles on serve but had still enough class and power to defeat Kamilla Rakhimova 6-2, 6-3 on Monday in a first-round match at the Australian Open. Gauff has won two Grand Slam titles but has never gone past the semifinals at Melbourne Park. She was knocked out in the quarterfinals last year.Gauff had six double faults in the first set against Rakhimova, and only one in the second set as she eventually found her range on serve. The American has struggled with double-faults and had 431 on the WTA Tour last year, by far the most of any player. No one else had more than 300. “I mean, it was just the first set,” Gauff said. “Only had one double in the second. I think both of us were struggling on the far side. The sun is right there, which I know for every time I play first on day here, that’s just how it is.“But once I got through kind of the first game, I had like three doubles in the first game, and once I got through that game, I mean, it was pretty much smooth sailing from there. Maybe I would have liked to put more first serves in the court, for sure.”The 21-year …