Liam Cooper has hailed the impact of Leeds United head coach Marcelo Bielsa and says he feels in the "prime of his career" following a Scotland call-up.
Steve Clarke has included the 27-year-old in his 23-man squad this month, which is the first time Cooper has been involved in the international set-up north of the border for two years.
Cooper, though, is yet to handed a cap by the country he represented at youth level and qualifies for through a grandparent.
United's club captain has been brought in from the cold by Clarke after former Tartan Army boss Gordon Strachan overlooked his services.
Scotland will take on Russia (September 6) and Belgium (September 9) as part of their Euro 2020 qualifying campaign.
Should Cooper be handed an opportunity, it will be his first appearance for Scotland in 10 years having featured in an Under-19s defeat to Iceland in September 2009.
“He [Bielsa] has brought my game on in so many levels,” Cooper said.
“I’m the fittest I’ve ever been and feel like I’m coming to the prime of my career. Leeds are a very demanding club so stepping up to international football will be nothing new.
"A lot of the credit for the call-up has to go to the manager and his staff. The way they have brought me on as a player and given me the responsibility of captain has been invaluable.
“Steve Clarke is going to have his own ideas but as a player you have to be adaptable to different styles. At Leeds we play different formations and I feel I can play any position in a three or a four.
"The biggest thing with the manager is fitness. He wants us to be able to run and make options. We attack, we attack… and we attack. We attack from the back so you have to be on your game.”