Rose Zhang wasted no time on the LPGA Tour.

Even though she didn't have her best round on Sunday, Zhang more than lived up to the hype in her first professional start in New Jersey.

Zhang, arguably the best women’s amateur golfer in history, held on to win the Mizuho Americas Open on Sunday afternoon at Liberty National Golf Club. The 20-year-old former Stanford star posted a 2-over 74 in the final round on Sunday and beat Jennifer Kupcho in a playoff to win in her professional debut.

"What is happening? I just can't believe it," Zhang said on the Golf Channel. "It was just last week when I won NCAAs with my teammates, and to turn pro and come out here, it's just been amazing. I've enjoyed the journey ... I had so many cheers around me, all my friends and family. I'm just so grateful."

Zhang is now the first person to win on the Tour while making her pro debut since Beverly Hanson did in 1951, and the first to win in her first LPGA start since 2019. She's the first ever to win the NCAA Division I individual title and win on the LPGA Tour in the same season, something she did in just a two-week span. The win also gives Zhang automatic Tour membership, too.

Zhang entered Sunday with a one-shot lead, thanks to a 6-under 66 in the third round that got her to 11-under on the week. She started Sunday much slower, however, and bogeyed the par-3 4th.

Zhang rattled off 12 straight pars after that, though she missed what should have been an easy birdie putt at the par-4 16th. That birdie would have given her a two-shot lead with two holes to go.

Zhang then expertly saved par at the par-3 17th with a massive 10-foot putt to maintain her one-shot lead. While her drive at the final hole rolled into the fairway bunker, she landed her approach safely in front of the green. That set up a great look at an up-and-down par to win, though Zhang's putt was just right of the cup.

Kupcho’s drive on the first playoff hole landed in the high grass off to the right of the fairway. Zhang’s wasn’t much better, however, as her ball landed in a bunker off to the right. They both pitched out safely in front of the green, and Zhang chipped her shot up into about the same position she had it the last time. This time, Zhang got her putt to fall to save par. Kupcho matched her, however, so the pair went back to the 18th to play it a third time.

Both Kupcho and Zhang found the fairway the third time out, though Kupcho’s approach landed well short of the cup on the front side of the green. Zhang stuck her approach to about six feet from 180 yards out. Though she missed her birdie — she was the only player in the field on Sunday without one — Kupcho three-putted. Zhang's par was enough to seal her inaugural win.

"This golf course is rough," Zhang said on the Golf Channel. "I really got a bit of everything, got a taste of the pressure, got a taste of the wind. I tried to stay composed as always. I knew that golf was just a grind and you really had to dig deep, so once again that's what I did. I'm glad I'm here."

Kupcho finished alone in second after her 3-under 69 on Sunday. Hae Ran Ryu was a shot back at 8-under on the week.

Zhang dominated the sport as an amateur in recent years. She was the first woman to win back-to-back NCAA titles while at Stanford, and she set the single-season scoring record twice. She held a 69.42 scoring average in the 62 rounds she played collegiately, and she won 12 of the 20 college tournaments she played in. By comparison, Tiger Woods only won 11 times in his 26 starts while playing at Stanford. Zhang was also ranked No. 1 in the World Amateur Golf Rankings for a record 141 consecutive weeks before she turned pro officially this week.