In the hour following her first WTA title win, Britain’s Harriet Dart had little time to respond to the stream of congratulatory messages flashing up on her phone.

Most pressing was making a call to her proud parents, Nick and Susie, who had been watching the final with friends at their local tennis club in north London, and her sister Phoebe.

The next person she spoke to was 2013 Wimbledon champion Marion Bartoli.

Dart has been coached by the French former world number seven since the start of the season on a part-time basis, and she credits Bartoli for helping her achieve what some thought was beyond her.

On Sunday, with Bartoli watching from home, the world number 115 won the Guangzhou Open in China by beating rising Austrian teenager Lilli Tagger.

“It’s been quite incredible to work with Marion, and I was really fortunate she was open to working with me,” Dart, 30, told BBC Sport in a video call from Guangzhou.

“I’m obviously at a very different stage of my career to someone who is, say, 20. But I still feel I have a lot to improve and there are gains to be made.

“She really believes in me – that means the world to me. Seeing a Grand Slam champion having that belief has made me believe a lot more in myself.”

When Dart started working with Bartoli, she was ranked outside the top 160. The pair live close to each other in Dubai and spend training blocks together there when Dart is not on the road.

Dart and Bartoli, who has a young family, are not travelling full-time together on tour, but there have been opportunities for them to work on the ground, particularly during this year’s Grand Slam tournaments.

Dart says 42-year-old Bartoli still hitting the ball “really well” in practice is another benefit of the partnership.

In Guangzhou, Dart was accompanied by her fitness trainer Dario Gonfiantini and boyfriend Stephen Falck. Without her coach, Dart had to largely rely on figuring things out herself – with the help of Bartoli sending over observational notes.

Dart is projected to rise to 83rd on Monday after lifting the Guangzhou trophy to cap a stunning second half of the season.

Dart has won 19 of her 24 tour-level matches on the hard courts since Wimbledon, taking her overall record on the WTA Tour this season to 23 victories from 34 matches – the highest winning percentage of her career.

“More than anything, Marion is just a great person. She cares about me as a person first and foremost, as well as improving me as a tennis player, of course,” Dart said.

“It’s been invaluable and amazing for her to share her experiences to make me better.

“I’ve learned a lot from her and look forward to continuing to learn more. I hope we will be able to spend more weeks together next year.”

Dart reached a career high of 70th in the world in 2024, having made the Wimbledon third round and US Open second round, but has languished outside the top 100 for most of the past two seasons.

During this period there have been clear vulnerabilities with her game, with opponents learning they could take advantage of a slow second serve that tended to produce double faults.

There have also been questions about her on-court mentality and whether she could handle the pressure moments.

In Guangzhou, she answered those doubts with a series of gutsy wins where she needed to fight back from behind.

“She’s always had a fantastic work ethic and has always set the bar high with her professionalism,” Anne Keothavong, Britain’s women’s team captain, told BBC Sport.

“But there is certainly more belief and confidence now. She’s in a very good place.

“She’s been grinding away on the tour for a long time and it’s great to see someone who has put in a lot of time to succeed and win a big title.”

Keothavong named Dart in her squad for September’s Billie Jean King Cup Finals and although she did not select Dart to play in the tie, she was impressed by her ball-striking during practice.

Taking that level back on tour has helped Dart continue what has been an encouraging few weeks for British women in the Asian hard-court swing.

Sonay Kartal reached the final of a WTA 1000 event in Wuhan, Katie Boulter made the semi-finals at a WTA 250 in Osaka and now Dart has won her maiden title at WTA 250 level.

Last week, teenager Hannah Klugman won the biggest title of her career at the Wrexham Open – a W100 event on the second-tier Challenger tour.

“The way they’re all performing towards the end of the season – at whatever level – has been impressive,” added Keothavong.

“It’s not easy at this time of the season because there has been a lot of tennis played, but they’ve all capitalised and risen to the occasion.

“It’s great reward for all their hard work and is encouraging for British tennis.”