Naomi Osaka and Cori Gauff remain on collision course at Australian Open

Naomi Osaka and Cori Gauff, two of the most precocious talents tennis has had in many years, are on track to meet in the third round of the Australian Open on Friday. The defending champion will start favourite, having beaten the American teenager handily at Flushing Meadows six months ago, but will take nothing for granted.

They won in contrasting styles on Wednesday, Osaka having the easier time of it over two sets against the unseeded Saisai Zheng in an hour and 20 minutes on Margaret Court Arena, while Gauff, the youngest player in either draw at 15, had to dig deep to beat the seasoned Romanian Sorana Cirstea, 4-6 6-3 7-5, in a thriller that lasted just over two hours on the Melbourne Arena.

Related: Australian Open day three: Djokovic and Barty cruise through the afternoon - as it happened

“It’s amazing what different personalities can bring to the sport,” Osaka said of Gauff. “Since she is so young, she has brought so much interest and a new wave. She played doubles in one of the stadiums at the US Open last year and it was full. That is not normal and I don’t think it is something that can be taken for granted.”

Gauff, still riding high after putting Venus Williams out of a slam in the first round time for the second time, said courtside of Osaka, “I know what to expect in the next round. She’s a great competitor. I know it’s going to be a good one.”

She paid tribute to the crowd for lifting when she was love-three down in the deciding set. “It’s amazing. I didn’t think I’d get so much support in Australia. They cheered me on to win. I don’t know why, but I’m glad I have their support. I have that will to win. My parents always told me I can come back. I was looking at my dad the whole match. He kept saying, ‘Come on kid’.”

Osaka, who entertains as much in her post-match deliberations as on the court, said after her 6-2 6-4 win, “I got very frustrated in the second set, and it’s something that I knew would happen, but I didn’t know the scale, like, what she would do to make me frustrated. She was slicing and dicing and getting everything. I was, like, ‘Can I just hit a winner already?’.”

She hit 20 of them, to Zheng’s seven, and converted half of her 12 breaks in what, from outside the court, looked like a routine win – even though she had to skip to avoid stepping on ... an insect.

“There are a lot of birds on that court,” she said. “When I was practising, Wim [Fissette, her coach] tried to move a bug and it flew away, but then the bird just ate it mid-air. I don’t know why I’m telling you this, but in my mind it fits the story. I just didn’t want to step on it during the point, because I wasn’t sure how far back I was going to go.”

Osaka has switched coaches again, from Jermain Jenkins to Fissette, who helped Johanna Konta to the Wimbledon semi-finals in 2017 and recently left Victoria Azarenka – which is part of the merry-go-round for hired help on the women’s tour. Sascha Bajin, who hit with Serena Williams for many years, coached Osaka to her first slam in New York two Septembers ago.

Related: Ashleigh Barty strolls into Australian Open third round with easy win

Bajin has since joined the exciting teenager, Dayana Yastremska, who made the final in Adelaide against Ashleigh Barty on Saturday, but lost on Wednesday to Caroline Wozniacki. The 29-year-old Dane, who retires from the game after this tournament, came from two breaks down in the second set to win, 7-5 7-5, and is one win away from a fourth-round match against her best friend, Serena Williams – if the American beats the Slovakian world No 70 Tamara Zidansek.

Heather Watson won her postponed first-round match, conquering the swirling wind on an outside court, and the steady tennis of Krystina Pliskova. She struggled at the start, losing her serve twice but made it tough for Pliskova in a stubborn passage of play at the end of the set, forcing her to save two break points before getting over the line. Watson took that energy into the second set and dominated most of the exchanges, breaking to level at a set apiece.

Pliskova was now fading under the consistent pressure from the back of the court, as Watson rallied her into submission in the third. The mistakes piled up for the languid Czech, who continued to go for her shots but found the net an inconvenience. A final wayward shot from the baseline ended her agony.

Watson out-served her, made fewer mistakes and hit more clean winners, including nine aces in just under two hours to win, 4-6 6-3 6-1. It was an impressive, solid performance to go with her run to the semi-finals in Hobart last week and, given she looked stronger as the match went on, should be in good shape, mentally and physically, for Elise Mertens in the second round.

“It was super windy today,” Watson said. “I felt prepared because it was like that in Hobart a lot of the days. Being the first-round match and it being postponed, I was a bit nervous in the first set, a bit tense. After the first set, I managed to loosen up, relax and start enjoying it. I thought my game improved more and more as the match went on.”

She said growing up in windy Guernsey has helped her play well in such conditions. “I don’t mind the wind at all. The way I play - slice, drop-shots, change of pace - I think it works well in the wind. And I’m patient.”

She next plays the Belgian world No 17 Mertens, who finished strongly to beat Danka Kovinic, 6-2 6-0, in under an hour.

“I played her last week, played her a few times in the past,” Watson said. “She’s a great player, very solid. It will be a tough match. It will give me confidence to know that I can beat her, especially if it gets close in those tight moments.

“In Hobart against her, I just stayed calm, stayed there every single point. That’s what you’ve got to do, especially against a player like her. She’ll be there every single point as well. I’ve got to be as aggressive as I can.”

Watson said she took inspiration from watching Harriet Dart win a tough three-setter in her opening match on Tuesday night. “She did brilliantly. She looked mentally so strong. The score was close but I felt like she was always going to win it.”