SYDNEY — Defending champion Angelique Kerber cruised into the Sydney International third round Tuesday as she targets back-to-back titles, while world No. 5 Sloane Stephens narrowly avoided a shock loss.

The second seeded German was made to work hard in the opening set against Italy’s Camila Giorgi, but took control in the second to ease through 7-6 (7/3), 6-2.

America’s Stephens battled back from the brink of a defeat to beat 72nd-ranked qualifier Ekaterina Alexandrova in their first round clash.

Less than a week before the Australian Open she was on the ropes with Alexandrova winning the first set to love and serving for the match in the second set.

But Stephens somehow rallied to win 0-6, 7-6 (7/3), 7-6 (7/3).

Earlier, two-time Wimbledon champion Petra Kvitova avenged her US Open defeat to in-form Aryna Sabalenka.

The Czech, who slumped to 29 in the world after being attacked in her home by a knife-wielding man in 2016, has battled back to number eight and was encouraged by her 6-1, 7-5 win over the Belarusian.

There was no such joy for 2017 French Open winner Jelena Ostapenko, whose poor form continued in a 6-3, 6-3 defeat to Australia’s Ash Barty, who is rewarded with a second-round clash against world No. 1 Simona Halep.

After picking up a thigh injury at the Hopman Cup, Garbine Muguruza — another major winner — safely negotiated her first-round encounter with fellow Spaniard Carla Suarez Navarro 6-3, 6-4.

She later pulled out of the tournament, citing an unspecified illness, giving her next opponent Kiki Bertens a walkover into the third round. In the men’s draw Australian teenager Alex De Minaur, a finalist last year, continued his preparations for the Australian Open with a 6-4 6-3 win over Dusan Lajovic.

Towering Americans Sam Querrey and Reilly Opelka are also through to the next round.

Statham stuns Chung

Four-time champion David Ferrer cruised through the opening round of the Auckland Classic Tuesday but South Korea’s Chung Hyeon suffered a stunning loss to local underdog Rubin “Jose” Statham 7-5, 6-3.

Ferrer, 36, brushed aside Dutchman Robin Haase 6-2, 6-1 to ease into the second round.

Defending champion Roberto Bautista Agut has pulled out of the event along with Tomas Berdych and Gael Monfils, leaving top seeded American John Isner as the main drawcard.

Tomic warms up

Bernard Tomic won his first competitive outing of the season Tuesday, beating American Jack Sock in a pre-Australian Open tune-up that will also see him take on fellow livewire Australian Nick Kyrgios.

In the opening match of the Kooyong Classic in Melbourne, 83rd-ranked Tomic overcame Sock in three tight sets 5-7, 6-4, 10-6.

Serb Janko Tipsarevic, meanwhile, returned to tennis after 15 months away following hamstring surgery, celebrating by beating Australian Jason Kubler 6-,4 3-6, 12-10.

In the women’s draw, American teenager Amanda Anisimova fell victim to a leg injury, retiring to hand Britain’s Katie Boulter a 6-4 win. — Agencies