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They have combined to take six English Premier League crowns in a row and are approaching the final step in one of the most enthralling title races in recent memory.
Yet as Chelsea and Manchester United head into the last day of a campaign that has never lacked for intrigue, both clubs should be aware that this weekend could be the last time when their absolute dominance is a given right.
The two modern giants of English soccer strutted their stuff in their own special way over the past eight months, and for only the second time in 11 years, we head into the season finales Sunday with the championship still up for grabs.
Chelsea can wrap it all up with a win, and the fact that Carlo Ancelotti's side has a relatively easy game – at home to Wigan – means there could be a paucity of drama at the conclusion of a truly dramatic campaign. United will be at home against Stoke and should also rack up a routine victory.
However, despite the collective muscle flexing from these two teams this season, this summer will be no time for either Chelsea or United to rest upon their laurels.
The sanctity of their illustrious status is under a measure of threat, with emerging imposters, political factors and aging squads providing the potential for a weakening of their powers. Of course, both sides will be the top two favorites when EPL hostilities recommence in August, but the assumption that next year's trophy will wind up in either Stamford Bridge or Old Trafford no longer can be made with such totality.
Manchester City is the club with the most obvious room for improvement, given the extraordinary transfer budget funded by its Arabian owners. City rose from 10th place last campaign to fifth this season.
Arsenal has been through its rebuilding phase and should be improved with Moroccan striker Marouane Chamakh on the way from Bordeaux and Robin van Persie recovered from injury. A title challenge by the Gunners would not be considered a huge surprise.
But many of the issues that could stymie Chelsea and United are internal.
Neither squad is getting any younger. United can't be so sure that another year of productivity can be squeezed from the legs of Ryan Giggs, Edwin van der Sar, Gary Neville and Paul Scholes. Chelsea can have as many as eight first-team regulars who were in place the last time the club won the league four years ago under Jose Mourinho.
Also, summer spending in West London and Manchester may not be as simple as a polite managerial request for funds.
Finances have been the hot topic surrounding United ever since its American owners, the Glazer family, took over with their stake purchased courtesy of heavy loans. Sir Alex Ferguson will not be given an open checkbook to invest with, and there are ever-present fears that the hierarchy will choose to cash in on Wayne Rooney just as they did with Cristiano Ronaldo 12 months ago.
At Chelsea, an EPL crown this year is almost something of a surprise. The Champions League trophy is the one that owner Roman Abramovich so desperately craves and that was the primary reason why he brought in Ancelotti, the European master who had tasted success twice with AC Milan. Instead, it was a familiar face, Mourinho, who swept into Stamford Bridge with Inter Milan and destroyed Abramovich's Champions League dream for another year in the round of 16.
Next season, Chelsea's focus on Europe will intensify with summer signings largely be based around expected effectiveness in the Champions League rather than domestically.
Nothing should be taken away from the Big Two this season. They held firm while others crumbled around them, most notably Liverpool, which is 21 points back of Chelsea and in utter disarray. But what has made Chelsea and United so great this season and in recent years has been their ability to adapt and improve, not just stand still.
More than ever this summer, a leap will be needed to stay ahead of the pack.
- English Premier League
- Manchester United