Japan’s Naomi Osaka said she was “in a state of shock” Saturday after holding her nerve to battle past Petra Kvitova to win the Australian Open in a three-set thriller that also delivered her the world number one ranking.

The fourth seed and US Open champion triumphed 7-6 (7/2), 5-7, 6-4 in a 147-minute epic over the Czech eighth seed to claim back-to-back Grand Slams and become the first Asian tennis player to hold the top spot.

She also became the youngest woman to become world no 1 since Caroline Wozniacki in 2010, and the first woman to win her first two Grand Slams back-to-back since Jennifer Capriati in 2001.

A rattled Osaka almost blew her title hopes with one hand on the trophy when she failed to convert three championship points after leading 5-3 in the second set. The never-say-die Kvitova forced a deciding set before Osaka finally edged ahead with a decisive break early in the third.

Match stats

Osaka – Kvitova

9 Aces 5

4 Double Faults 4

33 Winners 33

33 Unforced Errors 39

3/14 Break Point Conversions 3/10

116 Total Points Won 112