WIM Fissette, Angelique Kerber’s Belgian coach, had a warning for her competition last night: he still sees plenty of room for improvement in his star pupil. That is quite a claim considering the 30-year-old German is already a former World No 1 with three Grand Slam titles to her name after stunning Serena Williams on Saturday to claim her maiden Wimbledon title.

Fissette, who took Jo Konta all the way to the Wimbledon semi-finals prior to a parting of the ways late last year, has been a key figure in Kerber’s renaissance after dropping from World No 1 to outwith the world’s top 20 during 2017. He also holds a pretty handy record when it comes to outwitting Williams; in ten various encounters with previous clients Kim Clijsters, Simona Halep and Viktoria Azarenka, he can now break even against the greatest of all time.

“I’m still sure that we haven’t seen the best Angie,” said Fissette. “Physically she can do a lot better, her serve can still improve. The more she feels success with her offensive game the more she will use that as well. The older she gets, the more she will take experience into these matches to stay mentally calm.

“I think she can come back here and win again,” he added. “She has the experience now of being in the finals and winning a tournament like this. I don’t know how much longer she is going to play, probably she is not going to play ten more years but she is very dangerous as long as her motivation stays like it is right now, to become better every day.”

Fissette derives huge personal pride from his 5-5 personal head-to-head against Serena. “It’s not easy to beat Serena so I’m very proud of my record, I am five-all against her with my players so I’m very lucky to have worked with some quality players,” he said. “For me the most important issue is that the players start with the right plan but especially the belief that they can beat Serena. They all know how good she is but they all have to realise that she is human and that it’s possible to beat her. I feel that too many players go on the court against her believing that they can’t win and I don’t want that with my players.”

Kerber’s belief remained unshakeable despite a drive volley from Serena at close range which might have cut her in half. Considering the friendly rivalry between the pair, Fissette was surprised by the incident but insisted his player showed admirable calm not to let it affect her.

“I was a bit surprised that Serena really went for her - it looked like that from my point of view,” said Fissette. “They get along well, they have a lot of respect for each other. But everyone can get a little frustrated in the match when things are not going well. Serena loves to really let go. Maybe she didn’t mean it, I don’t know. Angie reacted well, she didn’t take it personally, she was not irritated, she continued to play her game and focus on herself.”

Only one major tournament remains on her to-do list – the French Open – if she is to claim the career slam. Fissette knows clay is her most difficult surface but feels there was a breakthrough at Roland Garros this year. “This year was huge success for her on the clay,” he said. “She wasn’t physically strong at the beginning of the clay season, she had no plan on how to play. We went to Rome five days in advance to play some sets and she was trying to hit winners on every second ball. I was like, ‘Angie, that is not going to work’. But one day in Rome she made the switch in her mind. She won the first set in Paris against by far the best clay court player in the world, Simona Halep. If you can do that, why can’t you maybe win it one day? It would be the most difficult grand slam for her to win but on the other hand how many really good clay court players are there at the top of women’s tennis? You have to keep believing.”

Kerber admits that she struggled with the trappings of fame after becoming World No 1 the first time around, but feels the experience will help her deal with things this time around. She is back to World No 4 this morning.”At some points it was completely too much for me,” she said. “Looking forwards I will deal with this situation a little bit differently.”

Having climbed up to the players’ box to share the moment with her parents Slawek and Beata, Kerber also spoke over the phone on Saturday with her grandparents, who own a tennis centre in Poland where she practised as a child. “I think they had a little bit to drink on Saturday night as well,”