Elena Rybakina has backed her former coach Stefano Vukov and expressed her disagreement with the Women’s Tennis Association as the governing body continued its investigation into the Croat on the eve of the Australian Open.

“I don’t agree with a lot of things what the WTA do in the sense of my relationship with Stefano,” said Rybakina, the sixth seed in Melbourne. “As I said before, I have never made any complaints or any of these things. I always said that he never mistreated me. That’s one thing. Since this situation is how it is now, I don’t really want to speak about this more. I want to focus on my matches here.”

Earlier this week, the WTA confirmed it had opened an investigation into Vukov owing to an alleged breach of its code of conduct. He is provisionally suspended from the tour, meaning he cannot receive accreditation and access the private player areas despite his original intent to attend the Australian Open.

Vukov was Rybakina’s first full-time coach and they worked together for five years, including when she won Wimbledon in 2022, until they split last August before the US Open. The Kazakhstani has since hired Goran Ivanisevic, Novak Djokovic’s former coach, and their collaboration began at the beginning of the year. Last week, during the United Cup, their first tournament together, Rybakina surprised many by announcing that Vukov would be returning to her team in an unspecified role.

Ivanisevic has, in an interview with the tennis blog Bounces, expressed uncertainty about his future with Rybakina. Ivanisevic said he had “told her what I think” but wanted to wait until the end of the investigation before saying anything further. “I am, for the moment, here,” he said. “What’s going to happen in a couple of days, I don’t know. Hopefully I will stay, and hopefully everything is going to be OK. But let’s take day by day.”

Rybakina faces the local wildcard Emerson Jones in the first round. As she continues her pursuit of a second grand slam title, she acknowledged this situation has not been easy to deal with and expressed her frustration at other coaches commenting. Rybakina was likely referring to the 22-time doubles grand slam champion Pam Shriver, who has repeatedly been critical of Vukov. The coach told the Athletic last week he had “definitely never abused anyone”.

“Definitely not the ideal situation,” Rybakina said. “I’m not happy with the whole situation, especially when still some coaches are making some comments, and the people who are not so close to the tennis world, they just see the comments and then they’re picking it up, make even more show out of this. I don’t think it’s fair, too. But my goal is here to focus on the matches. This is what I’m going to do.”

Meanwhile, Jannik Sinner’s anti-doping appeal hearing at the court of arbitration for sport (Cas) has been scheduled for 16 and 17 April. Sinner tested positive for clostebol last year but he received a favourable verdict in the initial independent hearing, which found him to have no fault or negligence, and was not given a doping suspension.

Sinner successfully argued that the presence in his system of clostebol, an anabolic androgenic steroid derived from testosterone, was a consequence of contamination through his physiotherapist, Giacomo Naldi, who he said had been using a medical spray containing the drug to treat a cut before inadvertently transferring it to the Italian through massage. The World Anti-Doping Agency (Wada) opted to appeal against the verdict to Cas. Despite accepting Sinner’s argument, Wada believes the case still warrants an anti-doping ban under the laws of strict liability, which hold every player responsible for the substances in their bodies.

Jack Draper, the British No 1, says he is fully fit and ready to attack the Australian Open after his off-season was disrupted by a hip injury and he was unable to compete in the United Cup during the first week of the season. This has been an eventful week for Draper on-site at Melbourne Park as he has trained with Novak Djokovic under the gaze of Andy Murray and the defending champion, Sinner.

“When I first came onto the tour, I remember putting my name down. I was in Miami. No one wanted to hit with me, which is a bit different now being able to play with top players,” said Draper. “My coach just sorted that out. I just came: ‘Who am I hitting with?’ ‘You’re hitting with these players.’ ‘Oh, wow.’

“It was amazing to be on court with Novak and Andy especially. Jannik I hit with a couple days ago. They just bring such a high quality to the practice court, as well. It’s really great to be able to spar with that kind of level of intensity and work ethic, just what they bring to the court. I was really, really, really happy to be able to play with them.”