Volkswacht Bodensee - Fritz crushes struggling Zverev at United Cup as US progress

German two-time ATP Finals champion Zverev slumped 6-1, 6-4 in just 64 minutes to the world number nine in Sydney as he continued his return from serious injury.

It followed a straight-sets loss to 81st-ranked Czech Jiri Lehecka on Saturday in his first competitive match since tearing three right ankle ligaments during his French Open semi-final against Rafael Nadal in June.

"It was tough to judge my level because I feel he's coming back from injury, he's a bit rusty, he was giving me a lot of free points," said Fritz, who had a breakthrough year in 2022 with titles at Indian Wells, Tokyo and Eastbourne.

"But I'm really happy with it. I'm sure it won't take him too long to fully get his form back."

The mixed-team tournament features 18 countries playing in Sydney, Brisbane and Perth.

The winners of the two groups in each city advance to a city final on Wednesday, with whoever comes through that making the final four.

Madison Keys followed teammate Fritz's lead with a dominant performance of her own, sweeping past Jule Niemeier 6-2, 6-3 for her second win of the season.

It ensured the Americans will face Britain in the Sydney city final.

"I think overall I played really solid," said Keys. "I just tried to make as many first serves as possible to make things as easy as a tennis match could be."

Zverev struggled with his movement, not chasing at full throttle, and appeared lacklustre in the first set, which was over in just 21 minutes -- he didn't win a single point off Fritz's first serve and only two off the American's second.

Olympic champion Zverev, who has dropped to 12 in the world from a career-high two before his injury, put up more of a fight in the second set as his confidence grew.

He held serve but was broken on the next to go 3-1 behind. Zverev worked his first, and only, break point of the match at 2-3 but Fritz held on and wrapped up the victory with an ace, serving out to love.

Later Monday, world number two Nadal will look to bounce back in Sydney from a three-set loss to Cameron Norrie as he seeks a first win of the season against Australia's Alex de Minaur.

Neither Spain nor Australia can advance from Group D, with Norrie's Britain already the confirmed winner.

Polish world number one Iga Swiatek and Switzerland's Belinda Bencic square off in a winner-takes-all tie that will decide Group B in Brisbane, while Italy need a win against eliminated Norway in Group E to advance at Brazil's expense.

In Perth, France and Croatia battle it out to win Group F, while Belgium need to defeat Greece at least 4-1 to qualify from Group A.

J.Horn--BTB