Americans Gauff, Mmoh plot second-round upsets in Melbourne

American teenager Coco Gauff will be eager to pull off another upset in her fledgling career when she faces fifth seed Elina Svitolina, while compatriot Michael Mmoh will be hoping to upset Rafa Nadal in the Australian Open second round on Thursday.

Gauff, 16, was one of the Australian Open's biggest success stories last year as she stunned Venus Williams, Sorana Cirstea and Naomi Osaka en route to the fourth round.

Early exits at the U.S Open and French Open last year halted her rise but she showed signs of returning to her best in her opening-round thrashing of Jil Teichmann to book a first meeting with Ukrainian Svitolina.

"I'm going to go out there and have fun," Gauff said. "She's a great player and I know it's going to be a tough match, but I'm just going to embrace the opportunity and try to play well under the pressure."

Another player looking to embrace the spotlight will be American qualifier Mmoh, who outlasted Serbian Viktor Troicki to earn a shot at world number two Nadal.

Nadal, bidding for a record 21st major, has won 25 of 26 matches against qualifiers at Grand Slams, although question marks remain over his fitness, with the Spaniard hampered by a back injury during his first-round victory against Laslo Djere.

If world number 177 Mmoh pulls off the upset, he will be the lowest-ranked player to defeat Nadal at a Grand Slam.

Australians Ash Barty and Daria Gavrilova will put their friendship on hold when they clash during the day session at Rod Laver Arena, with Greek fifth seed Stefanos Tsitsipas also in action on the main showcourt against local wildcard Thanasi Kokkinakis.

Russia's ATP Cup heroes open and close out the action at the John Cain Arena, with seventh seed Andrey Rublev facing Thiago Monteiro and fourth seed Daniil Medvedev meeting Roberto Carballes Baena.

Russian-born Sofia Kenin continues her title defence against Estonia's Kaia Kanepi.