Legendary F1 team boss Sir Frank Wiliams is suffering from pneumonia in hospital, though his team says he is making "a slow, steady recovery".
The 74-year-old was taken ill during the Italian Grand Prix weekend in September and has not been in the paddock since. He is recovering at home in England with daughter and deputy team boss Claire Williams, who has been in charge of the day-to-day running of the Williams team since 2013.
Chief executive Mike O'Driscoll took Claire Williams' place in the Friday team principals' press conference in Mexico, where he updated F1 media about the situation.
"[Sir Frank] has been a fixture in the paddock for so many years it's strange not to have him with us," he said. "He's had a tough time in hospital, he's making a recovery, a slow, steady recovery. We hope to see him back in Grove very soon, we all know how determined he is."
Claire Williams continues to be absent from the paddock as she sits at her father's bedside, though O'Driscoll believes she will be back in time for the season finale in Abu Dhabi.
"We expect Claire to be back [in 2016]," he said. "She's wanted to be close to home, close to Frank, but in this world you're only a phone call away, so we've stayed connected and she's part of everything that happens on a minute-by-minute, day-by-day basis. We hope to see her by the end of the year, hopefully at Abu Dhabi."
Sir Frank Williams is one of the most revered figures in F1, having led his independent team to nine constructors' and seven drivers' championships since its foundation in 1977. He was confined to a wheelchair in 1986 after suffering a car accident in France.