Williams chairman Adam Parr has resigned and will leave the Formula One outfit at the end of this week.
No reason was given for the surprise announcement, although team principal Frank Williams said Parr was seeking "better balance in his life".
"Williams Grand Prix Holdings PLC today announced that its Chairman Adam Parr has resigned from the Company," read a team statement.
"Adam will leave Williams on Friday 30 March 2012."
Parr arrived at Williams in 2006 as chief executive officer and stepped up to the position of chairman in 2010.
Only last month, Williams cited Parr as his most likely successor at the helm of his eponymous team, and today praised his outgoing chairman for his work over the past five years.
Williams said: "I asked Adam to join Williams at the end of 2006 to support me in the running of our team. Adam's achievements have surpassed my expectations and I must thank him for his service.
"Adam leaves us on good terms to pursue a better balance in his life for which I wish him and his family well.
"He has left us in good shape and I have every confidence that the Board and senior management team at Williams will continue to drive the business forward into a promising future."
Williams have shown signs of progress this season after a poor 2011 campaign, with the team running comfortably inside the top 10 in both Australia and Malaysia.
Parr has backed the Grove-based team to continue that upward trend in his absence.
He said: "I am very grateful to Frank for giving me the opportunity to work for Williams over the past five years - a period that has been both challenging and rewarding.
"Williams is a unique team with over 500 great-hearted and talented people and many superb partners in and out of Formula One.
"Williams is now set up to move forward and I wish everyone at Grove well."
Williams confirmed that Nick Rose, a non-executive director of Williams Grand Prix Holdings, was to be appointed non-executive chairman, while adding that Frank Williams would continue to oversee the company.