Alexander Zverev

SYDNEY — Alexander Zverev won both his singles and mixed doubles matches against Greece on Friday to lead Germany into the United Cup semifinals against Australia.

Zverev and Laura Siegemund beat Maria Sakkari and Petros Tsitsipas 6-3, 6-3 in the deciding mixed doubles to clinch Germany’s 2-1 victory after Zverev beat Stefanos Tsitsipas 6-4, 6-4 in singles. Sakkari beat former Australian Open champion Angelique Kerber 6-0, 6-3 to give Greece the early lead.

France will play Poland in the other semifinal match on Saturday. The final is set for Sunday, also at Sydney’s Ken Rosewall Arena.

Sakkari had lost three of her four previous career meetings with Kerber. But those defeats came before her rise to the world’s top 10 and 35-year-old Kerber’s break to start a family.

“I was just very solid from the baseline, doing what I have to do,” Sakkari said. “But of course I knew that Angie, because she’s very experienced, an amazing player, that she was going to find a way to come back. I managed my nerves really well, especially in that second set.”

Zverev is unbeaten in the season-opening mixed teams event.

“I had to come out aggressive. I knew that,” No. 7-ranked Zverev said of his game plan to beat Tsitsipas for the fifth time in 14 matches.

“He is one of the best, maybe the best aggressive players in the game,” Zverev said. “If he’s on the front foot, it’s extremely difficult to play against him.

“That’s why I have a not-so-good record against him because he is somebody that is difficult for me. But Germany and I needed that win and I’m happy about that.”