The likes of John Terry, Ashley Cole, Frank Lampard, Petr Cech, Michael Essien and John Obi Mikel all remain from the squad that he emotionally left following a 1-1 draw with Rosenborg in the Champions League back in September 2007.
The relationship with owner Roman Abramovich was at the time viewed as untenable, but just like childhood sweethearts who had drifted apart, Mourinho and his Russian boss have realised that the grass is not always greener on the other side.
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However, while the 50-year-old has described Chelsea as "home", there is no doubt that his old gaff has had an extension or two during his six-year exile in sunnier climes - it may not be as recognisable as he had hoped.
Where does Mourinho need to strengthen?
Where doesn't he? The obvious area is a goalscoring striker. The general consensus is that the Blues are just one clinical frontman away from having the strongest starting lineup in the Premier League, which seems a mad thing to say when they have a £50m centre-forward in Fernando Torres among their ranks!
Working backwards, the midfield is arguably where Chelsea are at their strongest. Eden Hazard, Oscar and Juan Mata are of the ability and age to flourish at Stamford Bridge for years to come, while Ramires is also effective in the engine room. There could be space for another holding midfielder, though, what with Lampard turning 35 before the new season starts and doubts over Mikel's future.
And now for the defence. If you look back through Mourinho's lineups since he rose to prominence at Porto, he has tended to favour a centre-back pairing which sees one being comfortable in possession, while the other is by no means a poor footballer, but his main role is head and block anything that moves - Ricardo Carvalho and Terry from the mid 2000s for example.
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At present, that does not exist. David Luiz is probably too much of a liability for Mourinho's liking (which could see him move into midfield) and at the other end of the scale, Gary Cahill, Branislav Ivanovic and Terry are the 110% men. The latter is also ageing and although he never had any real pace to lose, it's beginning to look like he is running through treacle. The supporters may adore JT, but as former Chelsea midfielder Craig Burley told Sports Mole in January, Abramovich could well be planning to part with the former England international this summer. Whether Mourinho feels the same, only time will tell.
A backup goalkeeper is also needed. Ross Turnbull and Hilario are inadequate replacements for Petr Cech, so that will need to be addressed. Mourinho will have got a good look at Thibaut Courtois, who has been on loan with Atletico Madrid from Chelsea over the previous two seasons. It is believed, though, that the young Belgian does not want to sit on the bench, so a bit of the Mourinho charm may be required to resolve that one.
Who will Mourinho look to sell?
The exit door at the Bridge could well be a revolving one over the coming months. Don't be surprised to see the likes of Victor Moses, Marko Marin, Kevin de Bruyne, Yossi Benayoun, Josh McEachran, Romelu Lukaku, Turnbull and Hilario all depart either on a loan basis or permanently.
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There are also a host other youngsters who have spent the last 12 months farmed out to all corners of the world and decisions will need to be made over their futures.
As mentioned earlier, one-club man Terry could also be sold if a certain Russian gets his own way - and let's be honest, when doesn't he?
Another player who could lose out from the Prodigal Son's return is Demba Ba. He only arrived from Newcastle United in January and to be fair to the Senegal international, he made an impression during the final six months of the season. But has Mourinho ever signed a centre-forward like Ba? It doesn't seem so. And would he be happy to play second fiddle for an entire campaign - especially when his nation is in pole position to qualify for next year's World Cup finals in Brazil?
Who will Mourinho look to buy?
It appears that Abramovich has gift-wrapped a present for Mourinho upon his return in the form of German international Andre Schurrle. The talk is that the attacker will join for a fee in the region of £20m soon.
You get the impression, though, that Mourinho will want a striker of his own, someone who will fire his side to glory. Radamel Falcao has opted for the tax-free life of Monaco and Robert Lewandowski is apparently bound for Bayern Munich, but Edinson Cavani could be a real possibility and that would also mean he was taking a top-class striker off his old foe Rafael Benitez, who has just taken charge of Napoli.
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Don't rule out Wayne Rooney wearing a blue shirt either. If Mourinho gets a sniff that the Manchester United striker is interested in a move to London, the 'Special One' is bound to act. After all, he'll be weakening a major domestic rival while strengthening his own team in a similar way that Bayern Munich seem to do every year.
Sami Khedira could also follow his former boss from Madrid to London, solving the midfield issue in the process. Rumours are that he has been offered a new contract by Los Blancos, but the German international is known to be loyal to Mourinho.
Defensively so many names have been linked with Chelsea - see our top five here. A centre-back will be high on Mourinho's wishlist, with a raid on his former club Porto for Eliaquim Mangala said to be in the offing.
Mourinho spent £150m during his first two years at Chelsea. He may not spend that much this around, but whatever happens, you can bet that it will be an interesting few months down the King's Road. Hold on to your hats, Chelsea fans.