SAN JOSE, CA, USA - No.5 seed Donna Vekic shrugged off a mid-match blip to see past former World No.30 Misaki Doi, 6-4, 3-6, 6-4 and reach the second round of the Mubadala Silicon Valley Classic.

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"Today was not easy. I was struggling to find rhythm and Misaki was playing great, hitting some great shots, but I'm really happy to win in the end," she told Andrew Krasny during her on-court interview.

Playing her first hardcourt match of the US Open Series swing, Vekic was up a set and break before the Japanese veteran fought back to force a third, ultimately advancing after two hours and 14 minutes on on Stadium Court.

"One guy in the crowd told me I need to get mean," she laughed. "When I first heard it, I thought he said I needed to get lean, and I was like, 'What?' But I probably needed a little more focus because I didn't serve it out, but I returned well in the last game."

The 23-year-old Croat is in the midst of a career surge, having reached her best ranking of World No.22 after making the second week of Roland Garros. Early losses to top-ranked Ashleigh Barty and eventual Wimbledon quarterfinalist Alison Riske hampered her grass court swing, but none of that seemed to shake her as she took a 5-2 lead to start the match.

"I'm here for the first time [in San Jose]. I left Europe in the middle of a crazy heat wave, so I'm finding it kind of cool here, at the moment!"

Doi recently returned to the Top 100 after winning the singles and doubles at the Swedish Open, a WTA 125K in Bastad, and played her best tennis from behind on Monday, getting one of the breaks back, but Vekic held firm to take the opening set.

Twice down a break in the second, Doi saved a game point that would have put Vekic eight points from victory and turned the match on its ear, winning four straight games to level the match.

Vekic nonetheless enjoyed a bright start to the decider, winning 12 of the first 15 points to move ahead 3-0, but soon found herself in trouble as Doi won three games of her own to tie things up.

Visibly frustrated, Vekic managed an impressive hold of serve and stood her ground as Doi missed back-to-back forehands to hand the No.5 seed a chance to serve for the match.

Doi wasn't done yet, winning four points in a row to break back once more but netted a forehand for Vekic to engineer three match points in the next game, converting her second with the help of a big forehand strike.

In all, she hit 26 winners to 39 unforced errors; while Doi hit 30 winners of her own, she also made 40 unforced errors and could only break six times to Vekic's seven.

Standing between the Croat and a spot in the quarterfinals is either French qualifier Harmony Tan or former World No.1 Victoria Azarenka, who face off later today.

"I think I'm going to have to improve my game because [Azarenka] is a great player, and very consistent. But she does give more rhythm, so in a way it might be easier to play her. Whoever I play, it'll be a tough match."