Finn Russell will leave Glasgow Warriors at the end of the season to take up what the club described as a "once-in-a-lifetime opportunity".
The Scotland fly-half has spent his entire senior career with the Warriors and was a Pro12 winner under Gregor Townsend in 2015.
Russell, who earned his 31st Scotland cap against New Zealand on Saturday, says his decision came from a desire to try something new, with the club announcing his departure in a lengthy statement.
Speaking to the Warriors' official website, he said: "I've shared so many fantastic moments with people who are now friends for life and to do it in front of the amazing Glasgow Warriors supporters at Scotstoun has been a dream come true.
"I've always wanted to experience as much as I can during what is a short rugby career. It was obviously a difficult decision to leave Glasgow, but I have the opportunity to take myself out of my comfort zone and experience a new culture and type of rugby.
"However, I am fully focused on Glasgow Warriors and will do everything I can to make my final season at Scotstoun a successful one."
Russell has been linked with a move to Top 14 side Racing 92, and Warriors managing director Nathan Bombrys admitted the number 10 has accepted a "lucrative" offer.
"Our club has an excellent track record of retaining our key players in recent years. However, in this instance Finn has decided to move on and accept a lucrative opportunity at another club," he said.
"We respect his decision and when the time comes we will thank him for his contribution to the club. It has been great watching him develop and grow wearing a Glasgow Warriors shirt.
"We know he will be fully focused on trying to bring another trophy to Glasgow Warriors this season."
|LeBron feeling worn down following Cavs loss|
|Rahm enjoys ´traditional golf courses´|
|Upbeat Spieth eyeing first win of 2018|
|Ovechkin leads Capitals into Stanley Cup Finals|
|Federer: Serena may be the greatest of all-time|
|Copa Libertadores Review: Gremio top group, River and Flamengo draw|
|Celtics rebound with key game-five win over Cavs|
|Warriors duo Thompson, Iguodala questionable for game five|
|Suarez: Iniesta hard to replace at Barcelona|
|Slipper suspended after positive cocaine test|
|Cardinals´ Ozuna absent from line-up because he overslept|
|Ancelotti a ´real coup´ for Napoli as Insigne thanks Sarri|
|Johnston ´amazed´ to see Liverpool in Champions League final|
|Fearless Loftus-Cheek embraces England pressure|
|Butland shocked by Hart absence|
|It´s a football club – Klopp on choosing Liverpool over Man United|
|Emery appointed after secret vote, says Arsenal chief|
|Klopp used Sevilla loss to inspire European title tilt - Henderson|
|Lineker, Stoichkov, Zico - the stars who blazed a J-League trail for Iniesta|
|Golf not fame drives McIlroy|
|De Villiers tributes led by Du Plessis, Kallis and Tendulkar|
|Buttler ´maturity´ is just what England need, says Vaughan|
|Fit-again Wawrinka returns to winning ways|
|Toulouse take giant step towards Ligue 1 survival|
|Jets will not punish players for incurring anthem-related fines|
|F1 Raceweek: Hamilton and Bottas looking to build momentum - Monaco GP in numbers|
|Steelers´ Antonio Brown advises Le´Veon Bell to ´show up´|
|Stephens out in Nuremberg, Stosur wins Strasbourg final rematch|
|Clippers extend coach Rivers´ contract|
|Ancelotti ´thrilled´ by Serie A return with Napoli|
|Carlo´s Angels? Napoli boss poses for unusual photograph|
|Brady will attend Patriots mini-camp despite OTA absence - Kraft|
|World Cup hero, Champions League master - the best of Andres Iniesta|
|Heading to my new home - Iniesta drops massive Vissel Kobe hint|
|Neymar fitter than Brazil expected ahead of World Cup|
|Jardim, Jokanovic reject Chelsea speculation|
|Knight Riders rally dumps out Royals in IPL eliminator|
|Salah, Mane, Firmino trio could blow Madrid away, says Redknapp|
|Napoli appoint Ancelotti after Sarri departure|
|NFL stars must stand for national anthem if on field|
|Mascherano laments Romero injury blow|
|´Mr 360´ De Villiers retires after going full circle|
|Ronaldo already a Real Madrid legend like Di Stefano - Nacho|
|Pep or Pepe? The Spanish footsteps Emery could follow|
|Arizona, New Orleans land Super Bowls as NFL draft heads to Nashville|
|Sarri thanked by Napoli chief De Laurentiis amid Ancelotti reports|
|You never know! - Vettel and Hamilton joke about potential Ferrari link-up|
|It´s a silly question - Carrick insists Pogba has Man Utd future|
|Yates protects Giro lead as Viviani takes fourth stage win|
|Ozil one of Arsenal´s biggest talents - Emery|
|Fastest ODI hundred, 278 not out - De Villiers´ best knocks|
|Deschamps: Rabiot has made a huge mistake|
|Arsenal players can challenge for titles, Emery insists|
|Salah can seal Ballon d´Or with Champions League win - Riise|
|I want Real Madrid to lose Champions League final - Alba|
|Leverkusen sign goalkeeper Hradecky|
|Arsenal job a ´dream come true´ for Emery|
|De Villiers hailed as a ´colossus´ after quitting Proteas|
|Benitez expects Lascelles to stay amid reported Liverpool interest|
|Saha tells Martial: Stay and work for Manchester United future|
|Atletico Madrid defender Savic undergoes hip surgery|
|Bess to make Lord´s debut against Pakistan|
|Vissel Kobe announce news conference amid Iniesta speculation|
|Yan Dhanda leaves Liverpool for Swansea|
|Injured Chung out of French Open|
|I wish he´ll come to PSG - Motta wants Buffon reunion|
|Guardiola praises new Arsenal boss Emery|
|Defensive woes, travel sickness and Ozil´s role - Emery´s Arsenal to-do list|
|WATCH: Anthony Joshua serves up Stephen Curry assist|
|De Villiers announces international retirement|