Matic: who should be joining him at Stamford Bridge
Jose Mourinho keeps talking about his season of transition.
With the Blues boss keen to reforge Chelsea in his own image, who are the six players that Chelsea simply must sign this summer?
Costa: proven goalscorer
Jose Mourinho's first six months back at Stamford Bridge have been dominated by the political manoeuvring to bring in a striker—and Diego Costa is the top target.
Mourinho doesn't believe the three goalscorers he has are good enough to make a realistic assault on the title, while the club are still desperate to give Fernando Torres one final chance.
With two years remaining on Torres' five-and-a-half-year deal, now would be the time for Chelsea to cut their losses. And he would be the perfect bargaining tool to persuade Atletico to part with Costa.
Given the differences in form and age (Costa is almost five years Torres' junior), much cash will have to head towards the Spanish capital along with Torres.
But, following the sale of Juan Mata, Chelsea have plenty to spend.
Hernandez: happy to head south?
Torres is not the only Chelsea forward who could be leaving this summer, with Samuel Eto'o on a one-year contract, and the Blues happy to listen to most offers for Demba Ba.
Ideally, Mourinho should be looking to have three forwards, all of whom are happy with their place in the squad. He does not need three first-choice strikers.
If Costa is secured as the No. 1 target man, and Romelu Lukaku is brought back into the fold as No. 2, then Javier Hernandez would be an ideal third choice.
Not the most technically gifted of players, his main asset is a rough-and-ready goal-scoring instinct—which has seen him score time and again off the bench against Chelsea.
While the Blues have been heavily linked with another unsettled Manchester United forward, this one might actually be willing to walk out of Old Trafford.
Terry: far from finished
The degree to which Chelsea look lost without John Terry is alarming for many Blues.
His absence creates a vacuum, both in defensive prowess, and in overall character.
Setting aside the caged-tiger mentality, in pure playing terms his omission means a lesser defender deputising. It's usually David Luiz, which means a lesser holding midfielder deputising for him.
Terry's contract is up this summer, along with those of Frank Lampard and Ashley Cole.
While the latter two of those three are starting to look expendable, that is far from the case with Terry—who Mourinho has brought back to almost his best.
Chelsea policy would be to offer him only a year, while he wants two, according to the Daily Telegraph's Jason Burt. Getting either deal in the bag would represent one of Chelsea's most vital summer signings.
Shaw: knows his way to Stamford Bridge
Ashley Cole has had an incredible eight seasons at Chelsea. For many, he has been the Blues' greatest player of that period.
But, at 33, it is clear he is not what he once was. Seeing him play this season has sometimes called to mind the last days at Stamford Bridge of that other world-class defender: Marcel Desailly.
Chelsea need to look for a long-term replacement, and Luke Shaw seems the obvious candidate.
There is no doubt that he is an incredibly gifted player, with a very mature style for an 18-year-old. It also helps that he grew up as a Chelsea fan.
Courtois: three years out on loan
Three years at Atletico Madrid have transformed the Belgian from one of Europe's finest young prospects into one of La Liga's best keepers.
Petr Cech is still one of the best, but the transition from old order to new has to begin at some point.
With no better a man manager than Mourinho at the helm—the man who masterminded the smooth transition from Carlo Cudicini to Cech himself—that time is this summer.
Mangala: made for the Premier League?
Chelsea have already started making plans for succession at centre-back, with the signing of Kurt Zouma. The Frenchman is seen as a long-term replacement for John Terry.
But, with David Luiz's future looking unclear, another central defender is needed.
The Blues have long been linked with Eliaquim Mangala, including this report from the Express' Charles Perrin the 23-year-old Porto defender recently called-up to the French national team.
Being big, solid, powerful and fast, he would seem to have all the assets needed for a Premier League defender.