Day four at the Australian Open

MELBOURNE (Reuters) - Highlights of the fourth day at the Australian Open, the first Grand Slam tournament of the year, on Wednesday.

IN-FORM RUBLEV EASES PAST SUGITA

Russian world number 16 Andrey Rublev, the winner of titles in Qatar and Adelaide this year, continued his strong start to the season with a 6-2 6-3 7-6(5) victory over Japan's Yuichi Sugita. He next faces David Goffin or Pierre-Hugues Herbert.

American John Isner, the 19th seed, beat Chilean qualifier Alejandro Tabilo 6-4 6-3 6-3 to advance.

ZVEREV GETS PAST GERASIMOV, THIEM DOWNS BOLT

German seventh seed Alexander Zverev moved into the third round of the Australian Open for the fourth straight year with a 7-6(5) 6-4 7-5 victory over Egor Gerasimov in his first career meeting with the Belarusian.

Fifth seed Dominic Thiem of Austria recovered from a mid-match blip to overcome Australian wild card Alex Bolt 6-2 5-7 6-7(5) 6-1 6-2.

MEDVEDEV SAYS UNDERARM SERVE CAN BE USEFUL

Russia's Daniil Medvedev said the underarm serve can be a useful weapon when executed correctly, after Spaniard Pedro Martinez unsuccessfully tried to catch him off guard in their second-round match on Thursday.

"You know... when Nick (Kyrgios) started doing it, people were, like, 'it's disrespectful for me, it's not for me'," Medvedev told reporters.

"It's one of the shots which he can use good sometimes, Nick. We saw some players do it last year when they're tight, because, it's easy to put the ball in like this... I just need to be ready for it sometimes and try to win the point."

INJURY-FREE BELLIS STUNS MUCHOVA

American 20-year-old Catherine Bellis, who recovered from multiple arm surgeries and returned to the WTA Tour in November after 20 months out, upset Czech 20th seed Karolina Muchova 6-4 6-4 to reach the third round.

She was joined by 17th seed Angelique Kerber who dispatched Australian wild card Priscilla Hon 6-3 6-2.

MUGURUZA ON A HIGH AFTER MOUNT KILIMANJARO ADVENTURE

Following her second-round win on Thursday, former world number one Garbine Muguruza reflected on her gritty effort to climb Mount Kilimanjaro during the off season.

"I wanted to have a reachable challenge, because if I pick another one, I put myself in a very risky situation... it was enough (of a) challenge to come back," Muguruza told reporters.

"I really like the experience to see myself in the middle of nowhere... having one clear thought just to keep climbing... it was a good experience."

BENCIC HAPPY TO PROGRESS IN TOUGH CONDITIONS

Swiss sixth seed Belinda Bencic said she was happy to beat Jelena Ostapenko under the roof of the Margaret Court Arena on a day when the outer courts were coated in red dust and rain.

"I'm super happy to get the match out of the way. I didn't know the courts were, like, wet and dirty and all that," Bencic told reporters.

"It was difficult today. It was sometimes sunny and then suddenly was almost raining. Then windy. Yeah, you just kind of have to accept it and go with it and try your best."

MEDVEDEV TOO GOOD FOR MARTINEZ

U.S. Open runner-up Daniil Medvedev, seeded fourth, overcame a slow start to ease past Spanish qualifier Pedro Martinez 7-5 6-1 6-3 and reach the third round.

Earlier, Czech second seed Karolina Pliskova made short work of Germany's Laura Siegemund, firing eight aces and 22 winners to seal a 6-3 6-3 victory in 86 minutes.

PLAY RESUMES ON OUTER COURTS

Play got underway on the external courts following a spell of rain. Czech 20th seed Karolina Muchova was set to begin her clash with American Catherine Bellis.

MUGURUZA RALLIES PAST TOMLJANOVIC

Spain's Garbine Muguruza blasted 34 winners as she quelled the challenge of local hope Ajla Tomljanovic 6-3 3-6 6-3 on Rod Laver Arena.

Play on the outside courts at Melbourne Park was suspended due to heavy rain.

MILLMAN EXPECTS FEDERER TO BE EXTRA DETERMINED

Australia's John Millman, who takes on 20-times Grand Slam winner Roger Federer next, recalled his famous victory over the Swiss at the 2018 U.S. Open but is well aware of how the 38-year-old responded on the grasscourts at Halle last year.

"He beat me in Halle on the grass there where he has a street named after him. He pretty much owns that tournament, I reckon," Millman told reporters on Tuesday.

"I'm sure he'll be confident in himself... he'll treat it (Friday's third-round meeting) as another match. Probably even he'll be that much more determined to nip me in the bud."

BENCIC MARCHES INTO THIRD ROUND

Swiss Belinda Bencic came through a tricky clash with former French Open winner Jelena Ostapenko, winning seven out of eight breakpoints to prevail 7-5 7-5. She will take on Spain's Sara Sorribes Tormo or Anett Kontaveit next.

Earlier, 19th seed Donna Vekic powered past France's Alize Cornet 6-4 6-2 to move into the third round for the first time.

PLAY DELAYED BY RAIN

Morning rain delayed play on the external courts for at least an hour but matches at the roofed showcourts proceeded only slightly behind schedule, with twice Grand Slam champion Garbine Muguruza taking on Australia's Ajla Tomljanovic in the early match at Rod Laver Arena.

Sixth seed Belinda Bencic was playing former French Open champion Jelena Ostapenko in the opener at Margaret Court Arena.

After a hot, gusty day on Wednesday, the weather forecast was for a cooler day of 21 degrees Celsius (70F) but with breezy conditions still to test players at Melbourne Park.

(Compiled by Ian Ransom and Shrivathsa Sridhar; Editing by Tom Hogue and Muralikumar Anantharaman)