Jose Mourinho is to be the subject of individual legal action from former Chelsea team doctor Eva Carneiro.
It means the Chelsea boss will have to appear at an employment tribunal unless there is an out of court settlement.
Carneiro was dropped from first-team duties after Mourinho said she was “naive” for treating Eden Hazard during a draw with Swansea.
Her lawyers are already suing the club for constructive dismissal.
The legal papers are expected to be served on Mourinho this week as part of separate, but connected, claims against him and against the club.
The doctor’s lawyers said neither she nor they could comment as the legal proceedings are active, while Chelsea have also not commented on the case.
The individual legal claim against Mourinho means Carneiro’s lawyers are alleging he was instrumental in Carneiro’s apparent demotion.
The incident in question occurred on 8 August, the opening day of the Premier League season, when Carneiro and head physio Jon Fearn rushed onto the pitch during Chelsea’s 2-2 draw with Swansea to treat midfielder Hazard.
Chelsea were already down to 10 men after goalkeeper Thibaut Courtois was sent off, and with Hazard having to leave the field after being treated despite appearing not to be badly injured, the team were temporarily reduced to nine men.
Mourinho was criticised for his comments but was cleared of using discriminatory language by the Football Association.
Carneiro revealed she had not been spoken to personally during the investigation, nor asked to provide any statement, however, the FA said she was given an opportunity.
Mourinho has come under increasing pressure on the pitch this season, with the reigning champions 15th in the Premier League table having lost six out of 11 matches.
