World number six Elena Rybakina's former coach Stefano Vukov has been provisionally suspended by the WTA while an investigation into his behaviour towards the player continues.
Earlier this week, Kazakhstan's Rybakina announced Vukov, who helped her win Wimbledon in 2022, was rejoining her team.
But the WTA has confirmed to BBC Sport the 37-year-old Croat is currently banned after allegedly breaching the WTA's Code of Conduct.
It is not clear whether Rybakina herself, or someone else, raised the complaint against Vukov which began the current investigation.
Vukov denies any wrongdoing.
"While the WTA does not typically comment on active investigations, we believe it is necessary to clarify this matter due to recent public statements that misrepresent the situation," the women's governing body added.