World Rugby chief executive Brett Gosper is to step down in January when he will take up a new role as head of the NFL in Europe and the UK.
Gosper's nine-year spell as CEO of the sport's global governing body has seen sevens reintroduced into the Olympics and the delivery of the first World Cup staged in Asia in Japan last year.
Chief operating officer Alan Gilpin will perform the role of interim CEO until Gosper's replacement is appointed.
"It's been a fantastic nine years. It has been an absolute privilege to have worked with so many talented and dedicated rugby people around the world," Gosper said.
"Rugby is a wonderful sport and World Rugby is a fantastic organisation, and therefore it was a very difficult decision to leave.
"But with a new ambitious strategic plan set to launch and the strong foundations in place to drive the sport forward beyond the pandemic, the time is right for me to begin a new challenge.
"I am proud of what we have achieved together as a rugby family. While I will miss working in the sport, my passion and enthusiasm for what rugby and its values mean to so many will never diminish."
Under Gosper's leadership, the 2015 Rugby World Cup saw 2.47m tickets sold and commercial and ticketing revenues in excess of £650m, generating more than £260m in profit for reinvestment in the global game.
Further records were set at Asia's first Rugby World Cup in 2019, with commercial and ticketing revenues reaching £750m, leading to a profit of £240m, and digital engagement totalling 1.7 billion video views.
As for his new role, Gosper added: "I am incredibly excited to be joining the very impressive and ambitious team at the NFL and helping the most valuable and watched sports league in the US win even more hearts in Europe and the UK."
Welcoming Gosper to the NFL, Christopher Halpin, NFL Executive Vice President and Chief Strategy and Growth Officer said: "We are tremendously excited to have Brett joining the NFL in such an important role.
"The UK has been a core market of investment and growth for the NFL over the last decade, and we believe broader Europe presents a number of similar attractive opportunities to expand the game and our fan base.
"Brett's exceptional skills and experience make him the ideal leader to build on our momentum and grow the NFL."