The first time I saw the 3-4-3 style system properly being used in England was the FA Cup final in 2013 when Wigan Athletic beat Manchester City in the final.
Roberto Martinez used the system and it was the first time I'd really seen it used.
When teams I played against used wing-backs, it actually would have been the old standard 3-5-2 with two up front.
The 3-4-3 that Antonio Conte has used with success at Chelsea is an interesting one. It's not the way that Conte would want to play. He says it himself that he sees himself as a back four man.
But he's used this system with Italy and used it with Juventus in the past and it's a system that really works for him. He can coach it really well and get the best out of the players that he's got.
It was needs must for him because of the way the team were playing before. They got hammered by Arsenal, lost badly against Liverpool prior to that, back four wasn't working and he felt they were too vulnerable.
He's changed the system and it's worked collectively and individually.
Eden Hazard was playing well anyway prior to that but he looks incredible within this 3-4-3 system.
There's no responsibility defensively on him. He knows he's got someone behind him and the man behind Marcos Alonso also has someone behind him in many respects as well. There's adequate cover down that side. So Hazard's been a revelation since the change and Diego Costa has been Diego Costa. I just love watching him play and I think he's been sensational again this season.
Manchester City manager Pep Guardiola congratulates Nolito after the Premier League match at Turf Moor, Burnley. Picture by Martin Rickett PA Wire/PA Images
With the back three, you've got a bit of structure and it helps David Luiz to step in. As crazy as it sounds, he's now got a bit of freedom from centre back because he doesn't have that total responsibility on him to defend, which I think everyone watching the game would recognise that one of David Luiz's biggest strengths isn't his defending. He struggles with his positional sense at times and can get caught out, whereas now he's got cover.
He's the best ball-player that they have in the back-three. He can play midfield as we've seen before at Chelsea.
But what's really been important is in front of the back-three. N'Golo Kante was good in the early stages of the season but looked ropey in the Arsenal game. But by and large he's had a good season.
But when we talk about Hazard being back to the best that he was at two seasons ago, Nemanja Matic is back! Back to the levels he was hitting two or three seasons ago as well.
Matic and Kante alongside each other is working well. Matic is able to step in like he was a couple of years ago and start attacks going forward.
So there are a number of factors within the system that make it work. And there hasn't been much change in terms of personnel recently. Conte has been able to use by and large the same team for the past six to seven weeks.
Chelsea have got spells where they have got to contain, and they can do it. But yet they've got that bit of creative spark as well.
Manchester City, like the Blues, are in their first season under a new manager. I feel this game against Chelsea is THE biggest game of the season so far for Pep Guardiola.
I was at Burnley last week and it was almost as if Guardiola's recognising that he's got to play different ways. David Silva, Kevin De Bruyne, John Stones and Ilkay Gundogan were rested. But I think those four will start in this match.
It suggests to me Fernando and Nolito won't start. So I'm not sure Guardiola's going to start Yaya Toure in the game because I can't see De Bruyne or Silva not starting this game.
City played a different way last week. They went long a lot. I don't think I've seen the goalkeeper Claudio Bravo kick as many times long in a game.
I think Guardiola maybe recognised that Burnley's strength was to go and press them and put them under pressure. They were giving it away a couple of times early on so there was a change of tactics.
Aleksandr Kolarov went so long so often too.
I don't see them necessarily doing that this week. I don't think Chelsea are going to press as much because last week it was Burnley who were at home and had to get a response after their result against West Brom.
That's the thing I'd be looking at this weekend. I think City will get a bit more freedom with them being at home and being able to play more freely.
So there's an intriguing thing really within this. When you bring four or five of the main players back into the City team. I think they will be a lot stronger than the previous week but I think they've also got one eye on the Champions League game against Celtic a few days later.
There have been a lot of personnel changes in the City side compared to Chelsea this season but that has mostly been down to the Champions League commitments. So Guardiola has to use his squad to cope with all the travelling. It does take its toll on a side. Chelsea don't have to worry about that.
But can City find a way of unlocking Chelsea? There are ways to hurt that system and Guardiola would have played against that system during his own career.
It's quite easy to see him changing and going for a three at the back himself. It can free up an extra man in midfield and they can get more bodies further forward.
But Guardiola, by and large, has mostly been a back four man. Whether or not we might see the inverted full backs coming into play where they go man for man with the two Chelsea wide men, Pedro and Hazard, we'll have to wait and see.
That would leave you on 2-on-1 defensively which still gives you that stability going forward and less responsibility for midfielders to track back in.
But when Everton tried to match Chelsea, it went horribly wrong in that 5-0 defeat. Everton cannot play three at the back against the caliber of Chelsea.
So it's going to be interesting to see what Guardiola tries to do and I'm looking forward to seeing Saturday's tactics.
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