Manchester United legend Ryan Giggs has transformed a player's approach to fitness, says Tony Strudwick.
Strudwick, the Reds' head of fitness and conditioning, is in no doubt of the veteran's standing.
"They're all great athletes and Ryan is just the perfect football athlete. He has a physical capacity that not many athletes possess. We look at running economy, which measures how efficient you are with your running, and his running economy is fantastic. He uses less energy per stride, so he's a smoother, more efficient athlete. That allows him to get through the number of games he has.
"On top of that, undoubtedly, what differentiates Ryan from a lot of athletes is his mental strength. Nothing fazes him. His mental strength, particularly at key moments of games, can be match-winning for us. And that makes him the go-to guy when we're under pressure. That's like Jordan or Redgrave. Under pressure, in a team environment, it's 'Give me the ball and I'll do it', like Ryan did against Norwich." He told manutd.com: "In any sport you get individuals - like Michael Jordan in basketball, Lance Armstrong in cycling, even Steve Redgrave in rowing - who move their sport on to another level through the longevity of their career.