Sinner joins forces again with former fitness coach

Italian world No.1 Sinner parted ways with Ferrara and physiotherapist Giacomo Naldi last year after the investigation into his positive tests for the banned substance clostebol in March.

"The decision has been made in alignment with Jannik's management team as part of ongoing preparations for upcoming tournaments, including the Cincinnati Open and US Open," a statement from Sinner's team said on Wednesday.

"Umberto has played an important role in Jannik's development to date, and his return reflects a renewed focus on continuity and performance at the highest level."

In February, Sinner received a three-month ban agreed with the World Anti-Doping Agency (WADA).

Sinner, who returned to action in May and lost to Carlos Alcaraz in the French Open final before beating him to win Wimbledon, said clostebol, which can build muscle mass, entered his system after Naldi applied an over-the-counter spray to a cut on his own hand before carrying out treatments on Sinner.

The spray had been given to Naldi by trainer Ferrara.

Sinner was cleared of fault or negligence by an independent tribunal, which accepted he had inadvertently been contaminated with the substance.

Speaking at last year's US Open, Sinner explained his decision to part ways with Ferrara and Naldi.

"Now, because of these mistakes, I'm not feeling that confident to continue with them. I was struggling a lot in the last months. I was waiting for the result. The only thing I need right now is some clean air," he said.

Ferrara, who had laid the blame for the incident on Naldi, worked with Sinner's fellow Italian Matteo Berrettini this year. 

Australian Associated Press