Stephens into Brisbane second round

Former US Open champion Sloane Stephens battled into the second round of the season-opening Brisbane International with a hard-fought 7-5, 6-3 win over Katerina Siniakova on Sunday.

Stephens, who reached a career-best ranking of three in 2018, broke her Czech opponent once in each set to book a second-round clash against 13th seeded Belgian Elise Mertens.

"It was obviously a good match," Stephens said.

"It's always really tough starting the year -- you just don't really know what's going to happen, so I think being able to come here and get a win was really nice.

"I'm really proud of that performance."

In other first-round matches, there were wins for Ukraine's Marta Kostyuk over Romanian Ana Bogdan 4-6, 6-3, 6-3, and Italian Camila Giorgi, who beat American Peyton Stearns 5-7, 6-2, 6-3.

Australian wildcard Arina Rodionova upset higher-ranked Italian Martina Trevisan 6-3, 6-2, while Anna Kalinskaya downed American Bernarda Pera 6-2, 6-1.

Russian teenager Mirra Andreeva beat countrywoman Diana Shnaider 6-2, 6-3.

Former world number one Naomi Osaka begins her comeback on Monday when she plays Germany's Tamara Korpatsch.

Only two matches were played in the men's draw, with Alexei Popyrin winning an all-Australian clash against Chris O'Connell 6-4, 6-7 (5/7), 7-6 (7/4).

Alexander Shevchenko beat Frenchman Luca Van Assche 6-3, 6-2.

Men's top seed Holger Rune opens his tournament on Monday against Australian Max Purcell while second seed Grigor Dimitrov faces former world number one Andy Murray.