Nelly Korda produced a flawless final round to claim a three-shot victory at the Gainbridge LPGA tournament in Florida on Sunday.
Korda -- whose elder sister Jessica won the LPGA Tour's previous event, the season-opening Tournament of Champions in January -- fired a three-under-par 69 to finish on 16 under.
The 22-year-old, whose father is former Czech tennis star Petr Korda, had opened up a one-shot lead on Saturday with a four-under-par 68.
On Sunday at Orlando's Lake Nona Golf and Country Club, she picked up where she left off in the third round.
Three birdies in her opening six holes gave her a healthy cushion at the top of the leaderboard, leaving her five shots clear at one stage.
She then reeled off 12 consecutive pars to remain in control and close out the fourth LPGA Tour victory of her career with her parents and sister Jessica rushing to congratulate her on the 18th green.
"Honestly I did not play very good golf today," Korda told a television interviewer moments after clinching her first career win on US soil.
"I just stayed really solid. I honestly don't know how I did it. It was definitely very stressful.
"Winning in front of my parents was a first too, so that was really nice."
Korda's 72-hole aggregate 272 left her three clear of Lexi Thompson and Lydia Ko who finished tied for second on 13 under.
Thompson had closed to within three of Korda with a brilliant eagle three at the par-five 11th, but a bogey on the following hole stymied her chances of mounting a charge down the stretch. Thompson finished with a four-under-par 68.
New Zealand's former world number one Ko stormed up the leaderboard at the start of the back nine with four consecutive birdies starting on the 12th hole, eventually carding a three-under-par 69.
World number one Ko Jin-young meanwhile finished five off the lead in fourth place on 11 under. Ko posted a one-under-par-71 after an erratic final round that included four birdies and three bogeys.
There was disappointment for Thailand's Patty Tavatanakit, who had started the day one off the lead.
The 21-year-old rookie faded with a two-over-par 74, with two bogeys and a double bogey on the front nine dropping her out of contention.
Tavatanakit finished on 10 under alongside Australia's Sarah Kemp, who shot a three-under-par 69.
Meanwhile, LPGA great Annika Sorenstam, who parred her final hole on Friday to make the cut in her first tour start since 2008, closed with a four-over-par 76, propping up the leaderboard on 13 over.