World No.1 Iga Swiatek became the first athlete to sign a worldwide brand ambassadorship with the beauty company Lancôme, she announced this week.

The four-time Grand Slam champion, entering her 99th week at the top of the WTA rankings this week, joins famous faces like Zendaya and Julia Roberts as ambassadors for the nearly 90-year-old cosmetics house. Her first brush with Lancôme came as a teenager, when she was gifted the brand's Idôle perfume.

The thought of joining A-list celebrities as a face of the brand never entered her mind at the time, she wrote in an Instagram post announcing the partnership on Tuesday. 

"I haven’t even thought that I will be announcing my cooperation with a beauty brand like this a couple of years later ... This is huge for me," she said. 

The launch was accompanied by a photoshoot featuring Swiatek by Gosia Turczyńska, who captured her posing in a black jumpsuit -- popping out from a white background -- while wearing bold red lipstick.

Also the first Polish ambassador for the brand, Swiatek also wrote that she was excited to be able to "celebrate [her] femininity" as a result of the collaboration.

"Because as a tennis player, wearing mainly sports clothes, I don’t have a lot of opportunities to do so," she said, noting that she will also collaborate with Lancôme on an initiative in Poland that will support women in the job market.

"She perfectly mirrors Lancôme’s expertise in the beauty world, and she is the voice of the young generation and an inspiration for all," a post on Lancôme’s social media channels said. "Iga has repeatedly demonstrated that she has worked hard for her success, masterfully setting boundaries and establishing her own rules.

"She has also repeatedly expressed that the situation of women, not only in sports but also in other dimensions, is extremely important to her, echoing Lancôme’s commitments toward women on their path to happiness and self-fulfillment."

Swiatek's deal with Lancôme adds to a growing sponsorship portfolio that also includes Rolex, LEGO and Visa. Last year, she was the highest-paid female athlete in the world according to Forbes; her $23.9 million in earnings topped a Top 10 that featured nine tennis players.