Watch: Video surfaces of 9-year-old Emma Raducanu hitting with Sonay Kartal 

Emma Raducanu is, without a doubt, one of the brightest prospects on the women's circuit. The teenager rose to prominence after her incredible run at the 2021 US Open, which she won as a qualifier.

A video has now surfaced on social media in which a nine-year-old Raducanu can be seen practicing with countrywoman Sonay Kartal.

Raducanu's speed and footwork were evident even at that age as she scampered across the court to retrieve everything that Kartal threw at her. The Brit even managed to turn the point around, but failed to put away a short ball and was punished by Kartal, who struck a forehand winner on the run.

Raducanu and Kartal, who were childhood rivals, have continued to follow each other's exploits on the senior circuit. The latter spoke highly of the newly-crowned US Open champion following her win last year, admitting that Raducanu has inspired her.

After US Open success, Emma Raducanu has continued to struggle

Now aged 19, Emma Raducanu will lead Great Britain in the Billie Jean King Cup qualifiers against Czech Republic later this week. Friend and one-time rival, Sonay Kartal, has also been included in the side. The Toronto-born player, who became the youngest-ever to win an under-18 ITF tournament at the age of 13, made her WTA debut last June.

Raducanu, meanwhile, became the first British woman since Virginia Wade to win a Grand Slam by triumphing at the US Open last year.

Emma Raducanu with the US Open Trophy

However, she has had a poor season post her maiden Grand Slam triumph, winning just four matches.

The youngster's inability to win consistently has attracted criticism from detractors. But Raducanu remains focused on her game, as was evident from her recent interview with The Telegraph.

"Maybe people watch the news or follow social media and see me sign this or that agreement," she said. "But I think it's pretty misleading because in reality I train at least six hours a day and spend that many hours at the club.

"I think it's unfair to me, but it's something with which I have learned to deal with," she added. "My commitments with sponsors are quite limited. It's three or four days every three months, so it's not a lot of time."

Raducanu has also found support from Canadian Eugenie Bouchard.

After her exploits at the Billie Jean King Cup, Raducanu will make her debut at the 2022 Stuttgart Open.