Top seeds Angelique Kerber and Andy Murray were both given a workout in the Australian heat as they overcome tough Ukrainian opponents to reach the second round.
Defending champion Kerber of Germany squandered a match point in the second set before battling past 51st-ranked Lesia Tsurenko, 6-2, 5-7, 6-2.
“First rounds are always tough,” Kerber said in a televised court-side interview at Rod Laver Arena in Melbourne on day one of the Australian Open. “But I always enjoy it here.”
Kerber’s ascent to the top of the women’s rankings started a year ago in Melbourne, when she came back from a match point down in the opening round to win the tournament.
She knocked 22-time major singles winner Serena Williams off the top spot after winning her second major of the season at the US Open in September.
Andy Murray
Murray, who overtook defending Australian Open champion Novak Djokovic as the world No. 1 at the end of last season, overcame Illya Marchenko in three close sets.
Britain’s Murray, seeking his first Australian Open title after five finals defeats, prevailed 7-5, 7-6(5), 6-2 against the 95th-ranked Marchenko as temperatures rose to as high as 30 degrees Celsius (86 Fahrenheit).
“I didn’t move that well,” Murray told reporters after the match. “That’s how it felt anyway. But sometimes that can also be down to the conditions, as well.
“The ball’s flying through the air a little bit quicker, so the ball is coming onto you faster than what it was the last few days. Maybe wasn’t reacting as quickly as I would have liked.”
Halep upset
Earlier, American Shelby Rogers — world No. 52 — pulled off the biggest shock of day one so far when she upset the fourth seeded Romanian Simon Halep, 6-3, 6-1.
Halep told reporters later on she had been struggling with tendinitis on her knee which hampered her movement.
Five-time Wimbledon winner Venus Williams, French Open champion Garbine Muguruza and the fifth-seeded Kei Nishikori all moved to the second round.
Former top-ranked Roger Federer will return from a six-month long injury break when he closes play on Rod Laver Arena against Jurgen Melzer.