Ryan Bertrand and Walker go back a long way, both at various levels of England age groups and as opponents in both the Premier League and Football League.
Bertrand won 10 caps for England Under-19s, while Walker won seven. The pair were both capped by England Under-21s, with Walker selected seven times and Bertrand 16.
Now the international team-mates and adversaries regularly share senior England duty, though while Walker trails Bertrand at other levels, he has won 32 to Bertrand’s 19 Three Lions caps.
On Wednesday, Walker will be up against a player he rates highly – with both attacking full-backs likely to come face-to-face a number of times on the flank at the Etihad Stadium.
“Ryan’s a year older than me but we came through the England youth set up together and we go quite far back,” said Walker.
“The earliest memory of Ryan I have is when I played against him for Sheffield United when he was with Reading, I think it was about eight years ago.
“He’s a top left-back and you don’t win the Champions League if you’re just an average player.
“He left Chelsea to go and play regular football and that’s what he needed to do,
“It says a lot about him as a person that he didn’t want to only play every now and then for Chelsea and I think he’s shown at Southampton what a talent he is.”