Grigor Dimitrov is trialling Radek Stepanek as a new coach, starting at this week's Rome Masters.
Dimitrov announced a few days ago that he was splitting with his former coach, Dani Vallverdu, who he had worked with since 2016 and reached a career-high of No. 3 in 2017.
The 27-year-old Bulgarian has had a poor season, experiencing injury and dropping to No. 48 in the rankings.
Stepanek was quoted by AFP as saying that they have agreed to work together until the French Open for now.
It is not apparent whether Dimitrov is still collaborating with Andre Agassi, who joined him as a coaching consultant in 2018. Agassi and Stepanek were joint coaches to Novak Djokovic in 2018.
There's been speculation that Dimitrov has spoken to Boris Becker about becoming his coach. The six-time Grand Slam champion is also a former coach of Djokovic.
Dimitrov is coming off a first-round exit to Taylor Fritz at Madrid. Jan-Lennard Struff is his first-round opponent at Rome.