MELBOURNE, Australia (AP) — Angelique Kerber had a straight-sets win for the first time in her first Australian Open title defense, starting her 6-0, 6-4 third-round victory with an eight-game streak against Kristyna Pliskova on Friday.

Top-ranked Kerber beat the other Pliskova twin, Karolina, in the final of the last U.S. Open to capture her second career Grand Slam title. Her first was here at Melbourne Park 12 months ago.

Kerber will next play 35th-ranked CoCo Vandeweghe, who reached the fourth round in Australia for the first time with a 6-4, 3-6, 7-5 win over 2014 semifinalist Eugenie Bouchard.

“I’m ready, I’m feeling good, I’m loving to play on this court,” Kerber said.

Eighth-seeded Svetlana Kuznetsova was broken twice while serving for the match before finally finishing off former No. 1-ranked Jelena Jankovic 6-4, 5-7, 9-7 in 3 hours and 36 minutes.

Two-time major champion Kuznetsova will next play No. 24 Anastasia Pavlyuchenkova, who beat No. 11 Elina Svitolina 7-5, 4-6, 6-3.

Vandeweghe recovered from an early break in the third set in a tense win over Bouchard, who was ranked as high as No. 5 in 2014 when she reached the semifinals in Australia and France and the final at Wimbledon.

The 22-year-old Canadian broke to open the third set and appeared to be in control, until Vandeweghe changed her approach.

After breaking back and holding in the key eighth game, when she saved four break points in a game that went to deuce eight times, Vandeweghe had the benefit of serving first with no tiebreakers in the deciding set.

She easily held for a 6-5 lead and then, after Bouchard had a game point, went on a roll to close with a big backhand winner on match point.

Vandeweghe has reached the fourth round and quarterfinals in the last two years at Wimbledon, but her run to the third round in Australia in 2015 was her best at any major not played on grass.

Still, she didn’t think the win to reach that level was particularly noteworthy.

“It was kind of expected, in my mind, to get the win and to get the victory and to move a step closer to achieving what I want to achieve for this year and also this tournament,” she said. “It’s just another opponent on the way to achieving my goal.”

Bouchard, ranked 47th ahead of the tournament, hasn’t gone past the third round of a Grand Slam tournament since slipping and falling in the locker room during the 2015 U.S. Open.

Australian Open organizers were briefed by Victoria state police over an incident in downtown Melbourne where a man deliberately drove into a street crowded with pedestrians, killing at least three people. Police said the incident, which occurred about three kilometers (two miles) from Melbourne Park, had no links to terrorism.

Organizers said the police had contained the incident and an offender had been arrested.

“Be assured there is no threat to the precinct,” a statement read.