After a nine-match run at the back end of last year when they could barely buy a league win and had dropped way off the pace for a Champions League spot, the advent of spring has seen them reach full bloom once again.
They have had to endure plenty of obstacles this season - the pressure of emulating their double success, exiting the FA Cup via yet another penalty shootout defeat, the sacking of Ray Wilkins, Ashley Cole's shooting incident, malaria - but right now they look a side galvanised by belief and high spirits flowing through the camp.
Manager Carlo Ancelotti has to take credit for that. Sure, it helps when you can spend over £70 million in the January transfer window, but the true benefit of the greater part of that outlay on just two players is yet to be seen.
Sunday's 2-0 win over Manchester City saw them leapfrog Roberto Mancini's team and move into third place. The last time the Blues were not in the top three with 30 games played was nine years ago.
City did what City do, rocking up at Stamford Bridge fully intent on claiming a draw which would keep them in the automatic Champions League places and continue their great recent run of results against them.
And for 78 minutes it looked as though it was going to work.
Once breached, City had only 12 minutes to respond to David Luiz's opener (which, incidentally, made it two league goals with as many shots on target for the Brazilian since joining Chelsea. Fernando Torres, eat your heart out). Throughout this season they have consistently failed to rouse themselves when faced with true adversity.
If they do not score first, then City almost invariably fall. They have recovered just four points after letting in the opener so far this season, whereas Chelsea have fought back to claim nine after going behind.
At the back, too, Chelsea have shown a little more resolve, dropping just seven points after getting on the scoreboard first compared to City's nine.
The average age of Chelsea's starting line-up was 28 years and 25 days, their youngest first XI since the November defeat at Anfield which kicked off that woeful winter run.
But it was the introductions of old guard members Didier Drogba and Nicolas Anelka which helped seal the victory, proving that this squad - written off as past it not so long ago - still has the wherewithal to keep plugging away and claim a huge win at such an important stage of the season.
Few outside London SW6 will be too convinced that the title is still within Chelsea's grasp - it is still looks a two-horse race despite the best and worst efforts of Manuel Almunia against West Brom, and Manchester United labouring to a 1-0 win over Bolton after putting in a performance as phoned in as Alex Ferguson's instructions from the Old Trafford directors' box.
But with a game in hand over City and the wind in their sails, Chelsea's team spirit looks set to carry them through to the end of the campaign.
Just as Ancelotti's team have got their act together at the right time, City look a team on the slide.
They have won just two of their last six in the league, and have not won on the road in any competition at all in 2011. That does not bode well for the FA Cup semi-final trip to Wembley to face United in a month's time.
With no date yet announced for the rearranged home fixture against Tottenham, the prospect of another late-season 'play-off' for fourth place against Spurs must be preying on the minds of City supporters.
Spurs, despite their own lacklustre domestic form, are just four points behind City with a game in hand on them.
With Mancini's row with Mario Balotelli reportedly escalating to the point where luggage was hurled last week - whereas Harry Redknapp hails his 'triffic' players every chance he gets and United continue to churn out results while their boss sits in the stands - do City have the necessary togetherness and will to battle together to take that big step further? It will be fun finding out over the next two months.
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Chelsea were given an extra reason to be cheerful before the City game courtesy of confirmation that John Terry had been reinstated as England captain.
Given the tossing around of the armband during the recent friendly in Denmark, the Stamford Bridge crowd's chants of "there's only one England captain" were a little ironic.
Little over a year after he lost the captaincy for a story which brought us the now ubiquitous phrase "revelations about his private life", the Chelsea skipper will once again lead his country out on to the pitch when England face Wales in Cardiff on Saturday.
Despite Fabio Capello saying last year that Terry might well become captain again but "not while I'm England manager", that is exactly what has happened thanks to Rio Ferdinand's absence through injury.
It is a U-turn that could be described as bold, hypocritical, pragmatic or foolhardy depending on your own thoughts on the matter, but the fact that the announcement was snuck out late on Saturday night, too late for the Sunday papers to give it any dedicated in-depth coverage, shows which line the FA might be taking on this.
It is truly bizarre that a) a player is being announced as England captain for the third time in their career and b) that announcement has been downplayed rather than shouted from the rooftops, accompanied by the obligatory pictures of the skipper draped in a St George cross and gurning for hordes of the assembled media.
Sadly, the 24-hour delay on Terry's reinstatement has taken the gloss off a special day for Wolves winger Matt Jarvis, who has received his first full England call-up for the match at the Millennium Stadium.
It's an early lesson in international football for Jarvis - when Terry has got the England armband, there is only one story in town.
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QUOTE OF THE DAY: "I have got no complaints about the result - it might not have affected the result, the way we played today. However, that was a really big, key decision for somebody 80 yards away - or 70 yards away at least - to overturn the referee. I knew and (fourth official) Martin Atkinson knew within five seconds that it was outside the box with the technology we have got. Surely it has got to be time for those sorts of things to be brought into play with all the technology we have got today." - Steve Bruce may not be too well acquainted with the dimensions of the Stadium of Light pitch, but it's hard to disagree with his assessment of the linesman's influence in Liverpool winning a penalty against Sunderland which sent them on their way to a 2-0 win.
FOREIGN VIEW: "Obviously, we made a mistake and the message is that we can't do this. I'm sorry from the bottom of my heart and there are situations which surprise me and leave me speechless." - Velez Sarsfield president
reacts after rioting fans caused Sunday's Argentine championship match against San Lorenzo to be abandoned amid reports that a fan had died in clashes outside the stadium before the game. The fixture is considered high risk and local authorities have banned the presence of away fans at recent meetings. However, this was lifted for Sunday's game at the request of the two club presidents.
COMING UP: Highlights of every one of the weekend's Premier League matches are now online, as are our round-ups of the top five goals and saves. Pundit Paul Parker will be giving his thoughts on the main talking points, and later this evening there will be live scoring of MK Dons v Peterborough in League One.