LONDON — Williams shareholder and executive director Toto Wolff is leaving to take a new role with Formula One rival Mercedes, the team said Monday. Wolff will relinquish his seat on the company's board but will retain his shareholding, Williams Grand Prix Holdings added in a statement. Reports in Germany said the 40-year-old Austrian, right-hand man to Williams founder and principal Frank Williams, would take on the role vacated by former Mercedes motorsport head Norbert Haug. Williams said his responsibilities at the former champion would be shared between members of the board's executive committee. Frank Williams thanked Wolff for his work, calling him “a key support” when he deputized for him at a number of races last season. “I would like to thank Toto for his hard work, dedication and commitment to the team during his time as a director of the company,” Williams said. “He was a key support to me as executive director last season, deputising at a number of races when I was unable to attend. However, positions such as the one offered to him by Mercedes do not come around often. “Toto has a long history with them and I certainly was not going to stand in the way of him accepting this once in a lifetime opportunity. Toto will retain his shareholding in Williams and will always have a place at Grove but make no mistake; we will fight him hard on the racetrack!”Mercedes has signed 2008 world champion Lewis Hamilton from McLaren for this season and also have Wolff's compatriot Niki Lauda, the three times world champion, as non-executive chairman of their board. Williams also has a new driver in Finland's Valtteri Bottas, a Wolff protege. Wolff's Scottish wife Susie still has a year remaining on her contract as a development driver for Williams and also raced in the German Touring Car (DTM) championship with Mercedes. — Reuters