Lampard? Luiz? Mikel? Which Chelsea stars should be sweating on their place as Blues re-sign £21m Matic from Benfica

By Charlie Skillen
What a difference three years makes.
Used as a makeweight in the deal to bring David Luiz to Stamford Bridge in 2011, Nemanja Matic is back at Chelsea in a £21million deal.
Critics have scoffed at the deal, using it to point out the Blues' pay-first-think-later flaws. But even Chelsea's extensive scouting team couldn't have predicted the Serbian would become one of Europe's most coveted midfielders.

Blue is the colour: Nemanja Matic poses with the Chelsea shirt after completing his £21m move

All-rounder: Nemanja Matic (right) can run past players with skill like here against Porto's Carlos Eduardo...

Remember me? Matic made fleeting appearances for Chelsea from 2009 to 2011 before being moved on

In the middle of a loan at feeder club Vitesse after some assured but fleeting cameo performances for the Blues, the decision to allow the midfielder to depart allowed him to blossom.
If Chelsea hadn't have sold him, he would be in no position to be walking into a Premier League title-challenging side.
A buy-back clause or a long-term loan mat have been preferable for the loose Abramovich purse-strings, but the fee can be looked at a couple of ways. It inflates Luiz's value to in excess of £40million, but is offset by a large profit set to be made on the out-of-favour Kevin de Bruyne.
Of more interest to Blues fans will be what difference he can provide to the team.

He's watching you: Jose Mourinho has identified Matic as the player to shore up his midfield gaps

Chelsea's 4-2-3-1 formation has suffered this at times this season when the sitting midfield two get overrun. None of the Blues' current line-up are really versatile enough to play really effectively in a midfield duo.
Jon Obi Mikel is clearly most noted for his defensive work. While he is able to start attacking moves - and frequently does - he lacks the pace and the creativity to consistently produce in the opposition half. He's best used as an anchor man.
Frank Lampard, meanwhile, is in the twilight of his career, and while he is still armed with a fantastic range of passing, he is most effective in the final third.
Playing in a holding two against a top side severely reduces his impact. At 35, he can't be expected to keep up with the game in that role.

Anchorman: Jon Obi Mikel (left), challenging Jeff Hendrick, is primarily a defensive presence

Club icon: But Chelsea's record scorer Frank Lampard has been used more sparingly at the age of 35

Apart from the seldom-used Michael Essien, whose series of unfortunate injuries have left him a shadow of the powerhouse starring in Mourinho's first spell in charge, that leaves Brazilian duo Luiz and Ramires.
Mourinho sees Luiz's long-term future at centre-half. He is currently enjoying a run in midfield due to injuries and the fruition of a partnership between Gary Cahill and John Terry. While Luiz has nothing to fear over his long-term future at the club, he is not a permanent solution in the middle of the park.
The energetic Ramires is another player who is not conducive to playing a midfield two. His boundless energy and dynamic running are a real asset and he has found a fan in Mourinho, but too often his average distribution is exposed without the buffer of a true holding midfielder.

Hairy moments: Brazilian star David Luiz has been playing in a midfield role, but is a centre half by trade

In Matic, Chelsea have signed (or re-signed) a player who can immediately slip into that role, offering a wide range qualities the other Stamford Bridge charges simply haven't got in their arsenals.
Standing at a powerful 6 foot 4, Matic is anything but your typical midfielder. With the Serbian entering the fray, getting overrun isn't an option.
A player of that size would often indicate a destructive influence, but the midfielder's calmness and technique on the ball means he offers much more than brute force.
He can not only tackle players, but is effortless at taking them on with the ball at his feet, and possesses a fearsome shot.

Boundless energy: But Ramires (centre), going past Hull's Robert Koren, is better in a midfield three

A kind of Mikel-Lampard hybrid, he could be the answer to the Blues' midfield dilemma - and he's tailor-made to fit into Mourinho's formation.
Immediately, he may be used more sparingly than thought while he gets gelled into the dressing room, but expect to see him as a first-teamer before long. Already knowing the ropes at Stamford Bridge will help immensely.
Who he replaces in the Blues' starting XI will vary vastly on the opposition.
Crunch title clash at the Etihad? Matic and Mikel would provide a poweful midfield to rival Yaya Toure and Fernandinho.

See you soon: Matic holds off Juan Mata when he faced his old club in the 2012 Champions League

Matic could dovetail with Lampard for a match against one of the league's lesser lights, or with Ramires if the opposition are there for the taking against bursts of pace.
One thing's for certain though, if Chelsea really are serious about fighting on three fronts in Mourinho's first season back, Matic's presence in midfield gives them a much better chance, and his challengers will have to accept less playing time.
Imagine if they'd have kept him...