Competitor: Serena Williams took on the 5k race named after her on Sunday morning in Miami’s South Beach

Serena, 33, chose an all in black Nike ensemble of shorts and zip-up top to compete in, and kept her long, dark hair back from her face with a matching black headband.

The world number one in the women’s singles game showcased her long muscular legs as she pounded the pavement with a look of steely determination on her face.

Meanwhile Venus, 34, brightened up the day in a hot pink top and patterned Lycra capri pants as she came out in support of her younger sister.

Afterwards the pair had just about enough puff left to get up on stage to perform karaoke.

Steely determination: The 33-year-old is known the world over as a fearsome competitor who hates to lose

Shorts: The tiny black Nike pants gave fellow competitors a glimpse of her long, muscular legs

Name badge: Just in case anyone didn’t recognize the world’s number one female tennis star,  Serena wore her name across her chest

Sister support: Venus in pink brightened up the day as she joined in the race too

Serena got the idea to host a race after running a 5k in Palm Beach, Florida last Thanksgiving, she told the Miami Herald.

All money raised from Sunday’s event will go to the Serena Williams Foundation to help underprivileged children

‘Every year, I do a run for Thanksgiving, the 5K or 10K, to kick-start my training for the year, and last year after running the 5K, I thought, ‘Wow, I really should do my charity based on running because it’s a really fun way to promote a healthy lifestyle,’ she told the Florida newspaper.

Smile: Serena’s performance was captured on a Go Pro camera held in front of her

‘People love it. You can run, walk, bring your family, it’s early in the morning. I love karaoke, so at my race, afterward you can go on the beach, relax, have Gatorade and sing karaoke.

‘It definitely helps your endurance on the court,’ she said. ‘You feel you can run so many miles, you can last three hours, four hours if you need to.’

She added: ‘I like running the shorter distances, like 5K. You don’t kill your body, but you can still feel part of the race atmosphere.’

Stamina:  ‘I like running the shorter distances, like 5K. You don’t kill your body, but you can still feel part of the race atmosphere,’ she told the Miami Herald

Great shape: Serena keeps up an intense training schedule to stay on top of her game which she begins each year at Thanksgiving

Charity: All money raised from Sunday’s event will go to the Serena Williams Foundation to help underprivileged children

Serena watched her best friend Caroline Wozniaki complete the New York marathon this year in just under three and a half hours.

When asked by Twitter followers if she had any plans to take on a 26 miler, single Serena told her followers: ‘My ass is too big.’

Tough going: The younger Williams’ sister feels the pain as she nears the end of the 6.5 mile course

Music motivator:  The sporting great kept her headphones in her ears the entire race

Looking fresh:  As she reaches the beautiful white sand beaches of Miami, the super fit star looks like she could go round again

Girls just wanna have fun: The sisters wear pink as they get up on stage to entertain the after race crowd with a bit of karaoke

Singalong: I love karaoke, so at my race, afterward you can go on the beach, relax, have Gatorade and sing karaoke,’ said Serena