World number one Jannik Sinner (23) on Thursday hailed his former physical trainer, who he sacked after becoming embroiled in a doping test controversy, as “excellent”.

Trainer Umberto Ferrara has now joined fellow Italian tennis player Matteo Berrettini, who is ranked number 35 and was the 2021 Wimbledon runner-up.

“Umberto is really a great trainer, that’s all I can say. He will surely do a very good job with Matteo who has had so many physical problems in the past,” said Sinner after his victory against Daniil Medvedev at the ATP Tour Finals.

Australian Open and US Open champion Sinner, 23, parted ways with Ferrara and physiotherapist Giacomo Naldi in March for their role in his two positive doping tests for an anabolic steroid.

The Italian explained to the International Tennis Integrity Agency (ITIA) that small quantities of clostebol found in his system were due to “contamination by a member of his staff (Naldi) who had applied an over-the-counter spray containing clostebol on his own hand to treat a small wound”.

Ferrara had supplied Naldi with the spray.

The ITIA accepted Sinner’s claim and he escaped a lengthy ban.

The World Anti-Doping Agency (WADA) has appealed the ITIA’s decision and is demanding a suspension of one to two years.