Chelsea’s former team doctor clearly heard José Mourinho call her a “daughter of a whore” in Portuguese when she ran on to the pitch during a Premier League match to treat an injured player last year, an employment tribunal has heard.

Dr Eva Carneiro, 42, is claiming unfair dismissal against Chelsea and sex discrimination and harassment against the former Chelsea manager following the incident against Swansea at the start of the 2015/16 Premier League season last August.

Lawyers for Chelsea revealed that Carneiro was offered £1.2m to settle her claims, but has instead decided to take the case to open hearing. In a skeleton argument, they said it was far more than “she could realistically recover even if she succeeded on all her claims”.

Carneiro’s decision to run on to the Stamford Bridge pitch to treat Eden Hazard meant the team was temporarily reduced to nine men and Mourinho afterwards called her and the physiotherapist Jon Fearn, who went on with her, “impulsive and naive”. Carneiro did not appear on the bench again for first-team duties and later parted company with the club.

In a skeleton argument referring to Mourinho, Carneiro’s lawyers claimed: “This is a tale of two employees: one good, one bad. The bad employee forces the good employee out of the job of her dreams and the employer does nothing to stop it. The bad employee berates, sexually harasses and demotes the good employee for carrying out her professional duties.”

In the first day of what is expected to be a 10-day hearing at Croydon employment tribunal, lawyers for the club and its former manager and those representing Carneiro made clear a key part of the case would hinge on the precise meaning of Portuguese swearing. An expert in Portuguese swearing will give evidence in the case. Mourinho is also expected to give evidence, as will the Chelsea chairman, Bruce Buck, and Chelsea director Marina Granovskaia, one of Roman Abramovich’s most trusted advisers.

The three-person tribunal heard that Mourinho called Carneiro “filha da puta” as she went on to the pitch to treat Hazard in the match against Swansea. Mourinho, in his witness statement denies that and claims he shouted “filho da puta” which means son of a whore and that it was not directed at the doctor.

“As she ran on to the pitch she heard clearly from behind her the words filha da puta,” said Mary O’Rourke QC, appearing for the claimant. “She’s a Portuguese speaker. It was not filho da puta, it was filha da puta … you say filha da puta when you are denigrating a woman. He is saying it to the back of the claimant who is doing something he didn’t like … that is the context.”

Daniel Stilitz QC, appearing for Chelsea, said Mourinho’s evidence was that he shouted filho da puta.

“Filho da puta is a phrase he often uses,” he said, adding that it meant son of a bitch. “There is no sexist connotation.”

He said that Mourinho used the phrase frequently at Chelsea’s training ground and during matches.

Chelsea and Mourinho will also argue that Carneiro would still be in her job if she had not resigned and said that she had been “provocative” and “refused to engage in steps to rebuild her relationship with Mourinho”.

“The claimant’s suggestion that Mr Mourinho’s language was gendered and targeted specifically at her is plainly unwarranted in the light of the footage,” their lawyers said in a skeleton argument circulated to the press. “Indeed she did not allege that the language used was discriminatory until well after the event. Mr Mourinho’s language was, again, far from unusual in the context.”

They also allege that in talks with Granovskaia, Carneiro said she was willing to “draw a line under what happened” in exchange for demands including a 40% pay rise to £400,000, a bonus scheme, an immediate return to the bench and a “substantial payment” in compensation for distress.

Mourinho was in charge at Chelsea until his sacking last December following a run of poor form for the team. He has since taken over at Manchester United and is expected to give evidence on Monday.

The case moved to the full tribunal after agreement was not reached at a private hearing in January. It is expected to run until 24 June and during the hearings, witness statements and documents – including texts and emails – are likely be made public.

Mourinho was cleared of using discriminatory language towards Carneiro following an investigation by the Football Association (FA).

Afterwards, Carneiro and the FA’s independent board member, Dame Heather Rabbatts, criticised the governing body for not interviewing the doctor as part of its investigation.

Carneiro has also had backing from Fifa’s medical chairman, Michel D’Hooghe, who contacted the doctor to offer his support and that of the world governing body. He has backed Carneiro’s insistence that she was simply doing her job.

The hearing continues on Tuesday when Carneiro is due to begin giving evidence.

(Guardian service)