US Open champion Naomi Osaka reached back-to-back Grand Slam finals with a hard-fought win over Czech seventh seed Karolina Pliskova at the Australian Open.

The Japanese fourth seed won 6-2 4-6 6-4 and will face Petra Kvitova, another Czech, in Saturday’s showpiece.

Osaka, 21, hit 15 aces and 56 winners in a confident display. The semi-final was played under the Rod Laver Arena roof as temperatures touched 40°C in Melbourne.

Osaka hit another forehand winner to give herself a match point at 40-30, shouting “come on” as she looked up to the sky and tried to compose herself, then hit what she thought was an 111mph ace down the middle.

After it was called out, Osaka challenged and clasped her hands together in hope as she watched the replay – and was left celebrating when Hawk-Eye showed the ball had clipped the line.

Asked about her feelings when Pliskova won the second set, Osaka said, “I kind of expected it a little because I’ve played her so many times and she has beaten me more than I’ve beaten her. I told myself to regroup and I managed to win.