Kerber’s expeditious victory over Keys should boost her already soaring confidence. She looks ready to run and run — a good idea against Halep — even if she joked on Wednesday that as a newly minted 30-year old, she needed to shorten the rallies.

“I am getting so old, so I have to be aggressive,” said Kerber, the No. 21 seed from Germany. “I cannot run for every ball anymore. I have to change something.”

She actually has changed plenty for 2018, splitting with her longtime coach Torben Beltz and hiring Wim Fissette, a veteran Belgian coach who has been a huge influence on other champions in the past, including Kim Clijsters, Victoria Azarenka and Halep.

Fissette does not tend to stay in his posts for long, but he is clearly an excellent analyst.

“She had great success with Torben but sometimes you need to change, just to hear a different voice,” said Barbara Rittner, the German Fed Cup captain. “It’s not a matter of the coach is bad or the player is bad. You just need to hear something new to respond better and try new things.

“Wim is a positive guy. He has a game plan, and he knows what he’s doing.”

The effects have been immediate. After winning four matches at the exhibition Hopman Cup team event in Perth, Australia, Kerber has won 10 straight official matches to start the season.

After winning the Australian Open and United States Open in her breakthrough 2016 season, she struggled for much of 2017. But Wednesday’s victory guaranteed that she would return to the top 10 after this tournament.