Story highlights

Kerber re-hired her coach in 2015

Since won 2 slams, Olympic silver medal

Now the new No. 1 in women's tennis

CNN  — 

“Movember” has come a month or so early for Torben Beltz – but the coach of new women’s tennis No. 1 Angelique Kerber is happy to let his facial hair keep growing and growing.

While the charity aims to promote awareness of men’s health issues by encouraging mustaches, Beltz’s hirsuteness represents the German’s surging career fortunes.

“I think I’m more superstitious than her maybe,” Beltz told CNN’s Open Court in New York a day after Kerber clinched her second grand slam title, both of which have come this the year.

“Because when she’s winning, I’m not shaving.”

Beltz grew a beard during the US Open, and had a bet with Kerber he’d sport a mustache during the WTA Tour’s Asian swing tournaments in Asia this month and the next if she won the title.

The 28-year-old responded by beating Czech surprise package Karolina Pliskova in the final at Flushing Meadows.

Kerber has turned her career around since reuniting with coach Torben Beltz.

Turning point

“In the past when I was playing I didn’t shave, and I still keep on doing this as a coach,” Beltz said. “If she keeps on winning for two weeks like here it’s getting really big my beard.”

They started working together when Kerber turned pro in 2003. Eight years later she reached the US Open semifinals, and in 2012 continued her breakthrough by winning her first two titles, making the last four at Wimbledon and rising to No. 5 in the world rankings.

They parted ways at the end of 2013, but reunited in 2015 after Kerber lost in the opening round of the Australian Open and dropped out of the top 10.

It proved to be the turning point of her career.

Under her compatriot’s guidance, Kerber became fitter and more aggressive. This season, she won the Australian Open (which she celebrated by jumping in Melbourne’s Yarra river after a bet) and the US Open, reached the Wimbledon final, clinched the silver medal at the Rio Olympics and knocked 22-time major singles champion Serena Williams off the top spot of women’s tennis after 186 weeks.

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Kerber talks to Beltz at a 2013 tournament in Sydney.

‘Good vibe’

Keeping Kerber on her toes with bets and games forms an important part of their player-coach relationship.

“We have a really good relationship,” says Beltz, who turns 40 in late November. “We have a good vibe. We can work hard together. And also off the court. We like to go to the cinema, we like to play games, backgammon and stuff.”

But once they hit the practice courts, Kerber is all business and constantly looking to improve.

“She wants to get something out of it,” Beltz says. “That’s a good attitude. Already now we’re thinking about some stuff because she’s No. 1, some new stuff we want to do. It’s not the end of the road – we really want to go forward now and take the next step to stay there, to play better tennis.”

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Stubborn

As well as her two grand slam titles, Kerber also reached the 2016 Wimbledon final.

Losing is part and parcel of a tennis player’s life, even if you are the No. 1 in the world, and at times Kerber can be “a little bit stubborn,” Beltz says.

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“You can see it on TV when she’s a little bit frustrated and she’s looking at me in some ways. But actually right now everything is positive. She won the US Open, she’s very happy, the coach is very happy too, so it’s really good now.”

On Tuesday, Kerber made a winning start to life as world No. 1, beating Kristina Mladenovic 6-7 6-1 6-4 to reach the third round of the Wuhan Open in China.