The potential match-up tomorrow between Manchester United's Gary Neville and Tottenham Hotspur's Gareth Bale - two contrasting full-backs at the opposite end of the career spectrum - will be fascinating subplot.
Judging by the way Stoke City's Matthew Etherington exposed the former England right-back on Sunday, Neville will be lucky to be selected by Sir Alex Ferguson.
If Bale displays the sort of marauding form that yielded a hat-trick last week against Inter Milan, whoever plays on the right-hand side of United's defence will have their work cut out. Bale's performance against Inter in the San Siro reminded me of the great Brazilian full-backs like Cafu or Roberto Carlos.
I once played against Cafu in a charity game at Old Trafford when he switched to central defence. He was supposed to be coming to the end of his career, but what a talent.
He was so strong, so fast. I wasn't slow, but I was compared to him. We had a laugh and he seemed a decent bloke - certainly not an arrogant big timer like George Weah. And anyone who can play for AC Milan at 38 has got to be a bit special.
Bale is like a one-man left-back and left midfield rolled into one.
It seems mad, but Harry Redknapp was not convinced about him when he arrived at Tottenham and was considering letting him go two years ago. That would have been a big mistake for Bale is one of the best of a new breed of full-backs whose duty to attack is just as important as that to defend.
Full-back is an increasingly important position. They may not command the same price as a striker, but they are not far behind. Why? Who does the goalkeeper look to give the ball to? The central defenders? The midfielders? The wingers? It's the full-back, who always need to be comfortable on the ball.
Football is all about space and creating it. A good full-back does that. When I was at Old Trafford, Gary Neville used to overlap David Beckham, knowing that he would not receive the ball. But he created space for Beckham to cross the ball because another player had to go with him. On the other flank Denis Irwin often played behind Ryan Giggs. To go ahead of Ryan would have been to move into his space where he would run at and beat defenders.
Beckham was not like Giggs, the type of player to go past an opponents, so Neville helped him. Neville was also an excellent crosser, which is an important attribute for a full-back, while Irwin could take free-kicks and penalties.
Between the pair of them they offered the team so many possibilities. Denis was a real unsung hero too. He gave so much to the team and his distribution was faultless.
He was the best full-back I played with and you always trusted his judgement.
I've seen the role of the full-back change. Nigel Winterburn was a good full-back for Arsenal, but he was a defender. I don't think he would fit in now when more is expected at the best clubs. Graeme Le Saux was one of the first full-backs who I would describe as a modern full-back. That he played a few times at left midfield for Chelsea showed the shifting role.
The likes of Daniel Alves and Maicon are among the best in the world. Like Bale, they have a great engine and are ultra fit. The Brazilians have influenced the modern attacking full-back, because they had players in the 1970s who used to get forward and score.
Not every full-back can be a marauding attacker and I've only mentioned players at top clubs.
If you play for a struggling side, then the full-back will be defending more than attacking. And rather than move into the opponents' half, he might hit a long ball down the channel for a forward to chase.
Then there are players like United's John O'Shea who is not the best full-back in the world, but he's so versatile. He can play left-back, right-back, central defender and midfielder.
But if you want to see a top level attacking full-back, look no further than Bale at the moment. He's only 21 and should get even better. I already think that he's good enough to play for an even bigger team like United, Barcelona or Chelsea. Bale has a great chance to show how good he is at Old Trafford in what could be a super game.
Andrew Cole is the second-leading goalscorer in Premier League history. His column is written with the assistance of European football correspondent Andy Mitten.