Wales pair Alun Wyn Jones and Justin Tipuric have retired from international rugby just four months before the World Cup.
Jones, 37, is world rugby's record cap holder - having played 170 Tests for Wales and the British and Irish Lions.
His announcement came just an hour after 33-year-old Tipuric revealed he was also quitting international rugby.
Both Ospreys forwards had been named in Warren Gatland's 54-man training squad for September's World Cup in France.
The pair were Six Nations champions in 2012, 2013, 2019 and 2021 while Jones won the first of his five titles in 2008.
Jones, who made his international debut against Argentina in 2006, has played 158 times for Wales and 12 Tests for the British and Irish Lions on four tours.
He led the Lions on the 2021 tour of South Africa and was skipper for the 2013 Test-winning decider against Australia in Sydney.
Jones captained Wales 48 times, including the 2019 Grand Slam when he was named the Six Nations player of the tournament.
He has also won three league titles with Ospreys and is set to appear for the Barbarians against a World XV and Swansea, his hometown club, later this month.
'Special memories'
"Having been selected in this year's preliminary Rugby World Cup squad, and after ongoing dialogue with the coaching staff and the WRU [Welsh Rugby Union], I have decided to step away from the international game," Jones said on social media.
"So, after 17 years I look back on special memories with Welsh greats and future Welsh greats.
"My grandfather and father both nurtured my passion for rugby in my younger days which has continued throughout.
"The opportunity to be professional in the sport I love was a dream come true, and to represent my home region, the Ospreys, and clubs within the region, namely Mumbles and particularly Bonymaen, who guided me in my favourite years, was beyond special and something for which I am hugely grateful."
'Pillar of the game'
Wales head coach Gatland said Jones had been an "incredibly special" player during a "phenomenal" 17-year career.
"His leadership, dedication and determination are second to none, every single time he has taken to the training pitch or put on the red jersey," he said.
"Al's passion and commitment for his country are limitless and he has been an important pillar for the game in Wales. He leaves a lasting legacy in Welsh rugby."
Jones' announcement swiftly followed the one made by his long-time team-mate and close friend Tipuric.
The three-time Lions tourist has not given a specific reason behind the decision, but confirmed he will continue to play for Ospreys.
Making the shock announcement on social media, he said: "During the off-season I've had time to reflect on my career and now seems the right time to step away from international rugby."
Tipuric made his Wales debut in 2011 and was to become regarded as among the finest all-round players of his generation.
Having emerged from the shadow of Sam Warburton to finally make the number seven jersey his own, he went on captain Wales last year.
'Privilege'
He was a key member of the Wales team that reached the World Cup quarter-finals in 2015 and semi-finals four years later. He was expected to appear at a third tournament this September having been named in Gatland's early squad.
"It's been a privilege to put on the Welsh jersey and have so many great memories," he added in the statement.
"I'd like to thank all the players and coaches that I've been fortunate enough to work with over the years and the wonderful support I've received from the Welsh public.
"I'm looking forward to spending more time at home and putting all my energies into playing for my home region the Ospreys."
Gatland described Tipuric as an "integral player" for Wales, who was never one for the limelight.
"He's quiet off the pitch, but his skill set and his work rate really set him apart from others," Gatland added.
"He doesn't like a lot of fuss, but he has made an outstanding contribution to Welsh rugby."
Ospreys said his decision to step down from Test rugby would be "sorely felt" by Welsh rugby.
"Known for his incredible work rate, agility, and rugby IQ, Tipuric has been an integral part of the Welsh national team for over a decade," the club said in a statement.
"He has become known as one of the finest open-side flankers in the game. He has contributed significantly to Welsh rugby's recent successes, including two Grand Slams."
Tipuric missed the last month of the regular domestic season with a foot injury sustained during Ospreys' Champions Cup defeat at Saracens in April.