Before the start of this season, Victor Moses had not played a league game for Chelsea for more than three years, but now he has a key role in the 3-4-3 system that has taken them top of the Premier League.

Moses, 25, has been out on loan at Liverpool, Stoke and West Ham during that time but he did not establish himself at any of those clubs either.

So his current situation is a huge turnaround for a player who, partly because of injury, started only 38 league games in the past three seasons, completing 90 minutes just 12 times.

He has a new lease of life because Blues manager Antonio Conte has given him a chance at right wing-back.

It is a new position for the Nigeria international, but it suits his strengths and, as he showed in Chelsea's 1-0 win over Middlesbrough on Sunday, he is not just filling in there - he is thriving.

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From winger to wing-back - why the switch is working

I played as a wing-back a lot during my career, particularly when I was younger in the mid-to-late 1990s when that system was last popular in the Premier League.

I used to enjoy it because, like Moses, it suited my game. Like him, I was more of an attacker than a defender and wing-backs have the freedom to get forward when they want.

Victor Moses' touches against Middlesbrough. He had three shots and put in five crosses

Yes, you have to be disciplined defensively and decide when to join the attack or hold back, but you have the freedom of the touchline and the ability to impose yourself on the game far more than you can as a normal winger.

By timing your runs you can come from deep with a head of steam and burst into great positions - the sort of thing that Moses was doing against Boro when he used his power and pace to great effect.

He was not directly involved in Chelsea's winner but it was his shot that led to the corner that Diego Costa scored from.

Why Chelsea's system suits Moses

It helps Moses that he has got a really stable set-up behind him thanks to N'Golo Kante and Nemanja Matic.

Moses knows at least one of them will drop in too, so Chelsea's three-man defence is rarely left without cover even if he does not get back.

So he can really bomb forward as much as he likes, especially in games like Sunday where his side were on top for long spells.

Boro defended very deep, Chelsea saw a lot of the ball and he could push high up the pitch.

The home side did not really deal very well with Chelsea's shape and their full-back Fabio was being dragged inside by Pedro.

Kante was also getting forward on the left and Gaston Ramirez did not know how to deal with him and Moses, meaning Moses got a lot of room.

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The attacking aspect of the wing-back role plays to Moses' strengths but he still dropped into defence when he had to at Riverside Stadium.

Moses is fast and fit and another reason he is good at getting back is that he has got his manager on the sidelines screaming at him.

He will not mind getting instructions like that because he is learning the position as he goes. Like Marcos Alonso on the opposite flank, Sunday was only the sixth game he has played there.

Moses is doing a very good job already, but he will definitely get better the longer he plays in that role.

Video analysis will help him develop too

I found part of the way I learned about playing wing-back was by watching my games, and looking at my movement at different moments - when I went forward and stayed, and seeing what I should have done.

Video analysis at clubs is just another part of the game now, but it was not always that way.

For me as a wing-back, it helped to develop my positional sense and see where I could pick up the ball to influence the game and hurt the opposition.

But it made the biggest difference to the defensive side of my game. Teams played 3-5-2 then, rather than 3-4-3, but the same applies - by doing the same, Moses will learn about the structure of his side in that formation.

He will see how to get in a position where he can either get back quickly to help his defence out or, ideally, discourage passes outside his centre-halves, which is where teams who play three at the back are vulnerable.

Tougher tests to come - starting with Tottenham

It might be a bit trickier for Moses when he is playing against a team like Liverpool who have got three up front because, if he still pushes up, there is far more of a risk of leaving his defence exposed.

But he will learn about that when the time comes and the next two weeks should provide a decent enough test when Chelsea play Tottenham and Manchester City.

I was at White Hart Lane on Saturday to see Spurs come back from 2-1 down to beat West Ham 3-2, and part of what got Tottenham back in the game was by pushing their left-back Danny Rose further forward.

Seeing Rose and Kyle Walker up against Moses and Alonso will be an interesting battle. It will be something new to the Chelsea pair, but I think they will be ready for it.

The same goes for the rest of the Blues team, who have not conceded a goal in their six-game winning run since Conte switched to this 3-4-3 system.

They did not have to do much defending against Boro other than a short spell in the second half, but still showed they can get through difficult spells in matches without conceding any clear chances.

At the same time they are able to break forward very quickly and obviously have the quality up front to hurt teams. I am really impressed with them all round.

I don't know whether they will win the league - the next two games might tell us more about that - but they are definitely going to be up there.

Kevin Kilbane was speaking to BBC Sport's Chris Bevan.