Venus Williams thinks it is "important" to look good on the tennis court because she doesn't want to be distracted from her game by worrying about her outfit.
The 38-year-old sportswoman - who has her own athleisure line, EleVen - doesn't want to be distracted by feeling self-conscious if she's not happy with what she's wearing during a match.
She said: "It's important. You absolutely want to look good.
"Can you imagine walking out on the court and feeling self-conscious that you look awful? If you're thinking about your clothes there's no way you can concentrate on your game."
Venus is just as ambitious about her clothing range as she is about her tennis career because she's so competitive.
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She told the Daily Telegraph newspaper: "Nobody wants to lose.
"It's the only way to live life, you have to be able to focus on what you can accomplish. The glass is full not half full."
And the tennis ace finds business strategy "extremely fun" and likes to get involved in that aspect of her line.
She said: "It's extremely fun, which makes sense, on court if your strategy isn't working you have to change it. I find it fascinating."
The sportswoman's sister, Serena Williams, recently launched her own fashion brand and Venus is a big fan.
She said: "We always share advice and insight. Her line is amazing, I love it. I'm super proud of her."
While Venus wears EleVen garments on the court, she's keen for buyers to be able to wear the clothing even when they're not doing sporting activities.
She explained: "We want to go seamlessly from the gym to the supermarket. I wanted to develop a collection to do that which allows women to feel confident in their lives while being their best.
"You feel good about yourself when you push yourself physically, when you get the results you want, when you achieve things."