Celtic captain Scott Brown has announced his retirement from international duty with Scotland.
The 31-year-old midfielder informed manager Gordon Strachan that he has opted to step down in order to prolong his club career.
Brown, who earned his 50th cap against Denmark in March, has been available for Scotland for more than 10 years following his debut in 2005.
"Firstly, I would like to thank Gordon for giving me the honour of not only playing for my country but captaining Scotland in the last campaign," Brown told the Scottish FA's website. "I also owe a debt to every Scotland manager before him who selected me - right back to Walter Smith handing me my senior debut and the national youth coaches along the way.
"Gordon has been one of the most influential people in my career and I did not want to let him or my country down but over the summer I had a lot of thinking to do. It's no secret that I've suffered some injuries in my career and once you get over 30 you have to protect your body more, in any case.
"I'm not the type of player who can coast half-heartedly through a game - I give 100% every time. Given the importance of this [World Cup] campaign for Scotland, and the challenges ahead at Celtic, I simply felt that I could not keep up both commitments without either my performances or recovery time suffering.
"Gordon understands this completely and I would hope the Scotland supporters understand my position, too. The personal disappointment of not reaching a major championship finals with my country was heightened this summer but we have a great squad of players and I am certain that we can really make a go of this campaign and qualify for Russia.
"I genuinely think we showed in the last campaign that we are good enough to compete with Germany, the world champions, and other nations who qualified ahead of us. I would like to thank the fans who travel across Europe to back us, my teammates and the backroom staff for their support and look forward to seeing them soon."
Strachan added: "Scott is one of the most wholehearted players I've encountered and somebody who puts the team ahead of himself. He is not the type to play within himself, either, and I understand and respect the decision he has taken. I have huge admiration for a player as selfless as he has been: to sacrifice family time and recovery time to help his country.
"We will miss Scott as a player, no doubt about it, but football evolves and it provides an opportunity for others to step-up take that responsibility. We'll miss him as a person, too, because his influence and popularity around the squad was integral to all that we did as a group."
The announcement comes a week before Strachan's squad announcement for next month's 2018 World Cup qualifier against Malta.
