Jose Mourinho moved to Stamford Bridge in July 2004, only two months after winning the Champions League with Porto, and became the most successful manager in the club's history.
He began his managerial career by working as an interpreter under the tutelage of the late Bobby Robson at both Sporting and Porto in Portugal, before following him to Barcelona.
Having impressed while in charge at both Benfica and Uniao de Leiria, Mourinho then returned to Porto as manager in 2002, where he led them to Uefa Cup and Champions League glory before moving to west London.
Charismatic and controversial in equal measure, Blues fans took the self-appointed Special One to their hearts instantly.
His first game in charge couldn't have been any tougher, with Manchester United the visitors to the Bridge, but an Eidur Gudjohnsen goal was enough to secure a 1-0 win, ensuring Mourinho's reign was off to a flying start.
We won six of our first eight games, drawing the other two, before losing 1-0 at Manchester City thanks to a Nicolas Anelka penalty, the only time we would suffer defeat in the league all season.
Mourinho settled on his favoured system of 4-3-3 after just one and a half games in charge. Most often he had either Drogba or Gudjohnsen leading the line, and Damien Duff and Arjen Robben on the flanks. Frank Lampard and Claude Makelele were outstanding in midfield, while Petr Cech in goal, and a defence marshalled impeccably by John Terry were virtually impenetrable.
Mourinho's first trophy was secured as early as February 2005, when we beat Liverpool 3-2 after extra-time in Cardiff to win the Carling Cup. We were knocked out of the FA Cup by Newcastle in the fifth round but still going strong in both the league and Champions League.
Arguably the toughest game of the season came up at Ewood Park, when a Blackburn side tried every trick in the book to upset the Blues' flow, with Robben in particular on the end of a terrible challenge.
Ironically, it was the Dutch winger who scored the only goal of the game, and the Chelsea players celebrated wildly with the travelling fans at the final whistle.
Big wins away at Everton and Norwich followed, while Crystal Palace, West Brom and Fulham were all beaten at home.
On 30 April we headed north to take on Bolton, only 90 minutes away from becoming champions for the first time since 1955.
After a stuttering first half performance, Lampard put the seal on a magical day by scoring twice to ensure Mourinho had won the title in his first season in English football, a truly remarkable achievement. We ended with the most points, and the best defensive record in the league's history.
The players' celebrations were fairly low-key given the fact we had a Champions League semi-final second leg to play at Anfield on the following Wednesday, but our luck was out that night, and Luis Garcia's highly controversial goal sent Liverpool through to the final in Istanbul at our expense.
Mourinho brought in Michael Essien, Asier Del Horno and Shaun Wright-Phillips prior to the start of the following campaign, as well as recalling striker Hernan Crespo from a loan spell at AC Milan.
It was the Argentinian who sealed the points on the opening day, scoring with a stunning strike in the last minute to beat newly-promoted Wigan 1-0.
After that first, highly successful campaign and among many warnings that retaining the title would be an even tougher task than winning it for the first time, Chelsea got off to a flyer, winning the first nine league games having not conceded in the opening seven.
When defeat eventually arrived, the team reacted with typical fortitude, going on another winning run that lasted 10 Premiership games and included a first league win at Highbury for over 15 years in our last game there.
Our Champions League campaign, however, hit the skids in February, when we were beaten 3-2 on aggregate by Barcelona in the second round.
It was business as usual in the league though, and while we did lose at both Midlesbrough and Fulham, we were scoring goals for fun, with West Ham, Everton, Tottenham and Liverpool all swept aside.
A win for the Blues at home to United at the end of April would secure back-to-back titles with first place in the table never surrendered, and so it proved, with Mourinho's side running out comfortable 3-0 winners. William Gallas scored early on, before second half strikes by Joe Cole and Ricardo Carvalho sealed the win.
As the players celebrated by embarking on a lap of honour around the pitch, Mourinho tossed his championship medal into the crowd at the Matthew Harding stand, undoubtedly making the day even more special for one particular person. Though the football didn't thrilled to the degree it had the season before, it was never really in doubt the title would remain at Stamford Bridge.
There were big name arrivals and departures at the club before the 2006/07 season. In came Michael Ballack and Andriy Shevchenko, while both Duff and Gudjohnsen moved on. Ashley Cole was then signed as part of a swap deal involving William Gallas at the end of August.
On the whole, it was another impressive season, but early defeats against Middlesbrough and Tottenham meant we were always chasing Manchester United. After losing 2-0 at Liverpool in January, we remained unbeaten for the rest of the season, but United surpassed our consistency levels and won the title by six points. With important players including Petr Cech and John Terry missing due to injury at times, Mourinho talked of playing 'survival football'.
More disappointment was to follow in Europe, where once again we were beaten by Liverpool in the semi-finals with the tie decided by penalties, but the Mourinho knack for silverware continued. We won the League Cup at Cardiff by beating Arsenal and in the first FA Cup Final at the new Wembley, he masterminded a tactical triumph over Manchester United, winning 1-0 in the closing the moments of extra-time at the end of a mammoth season.
Mourinho began his fourth season in charge in solid, if not spectacular fashion. New arrivals in the shape of Florent Malouda, Claudio Pizarro, Tal Ben-Haim and Steve Sidwell seemed low key compared with recent summers. Arjen Robben moved on for a record fee.
Scrappy wins against Birmingham and Reading ensured a decent start, but performances had been flat, and when we went down 2-0 away at Aston Villa, rumours were beginning to circulate that all was not well.
A 1-1 home draw against Rosenborg in the Champions League was to be Mourinho's final game in charge; the following night he was called to a meeting with the board and a mutual agreement was made to part.
Mourinho's spectacular tenure as Chelsea manager had come to an abrupt end but the fans were left with the satisfaction of knowing that for two years during it we were indisputably the best team in the land.
After spells at Inter Milan and Real Madrid with plenty of significant silverware won, he returned to his former job at Stamford Bridge in June 2013.