On Saturday the Premier League heavyweights square up in what could be the decisive game of the 2007-2008 season.
Defending champions Manchester United take a three-point lead to west London to face their title rivals Chelsea.
Victory for Sir Alex Ferguson's team would take them six points clear of Chelsea, with two games remaining, but United's vastly superior goal difference - 54 to the Blues' 36 - would effectively give them an unassailable lead.
However, if Chelsea triumph they would be level on points with United to set up a potentially thrilling end to the season.
BBC Sport weighs up the two protagonists ahead of the Stamford Bridge clash.
Both teams were slow out to the bell this season but picked themselves off the floor and look to be peaking at just the right time.
Manchester United's title credentials were being examined as early as August when they were held at home to Reading on the opening day of the season, drew at Portsmouth and then lost to their hometown rivals City.
Chelsea's wobbles came in September, with a defeat at Aston Villa and draws at home to Blackburn and Rosenborg in Europe, prompting the departure of manager Jose Mourinho.
When his successor Avram Grant started with a defeat and a draw, the Blues found themselves seven points off the pace.
But since then, Grant's Chelsea have been defeated only once in 28 Premier League outings and are currently on an unbeaten run of 18 league matches.
United, meanwhile, registered eight straight league wins after their early struggles and have got stronger as the season has gone.
They are the league's most prolific scorers and have the stingiest defence.
Both teams have had 20 clean sheets and since the turn of the year their records are almost identical.
Both sides drew in Europe in midweek, although Chelsea have had an extra day to recover.
Manchester United hold a three-point lead in the Premier League; Chelsea have the home advantage.
And what an advantage it is. They have not lost a league game at Stamford Bridge since Arsenal beat them 2-1 over four years ago - which could prove to be the crucial factor.
VERDICT: Round one to Chelsea
HEAD TO HEAD
Roman Abramovich's arrival at Chelsea in 2003 catapulted the club into a position where they are now the biggest rivals to United's English dominance, both on the field and in the transfer market.
MAN UTD IN LEAGUE AT CHELSEA SINCE 1992
P4 W D1 L3 GF 0 GA 5
P11 W5 D4 L2 GF 18 GA 14
They have shared the last three Premier League titles, Chelsea clinching the 2005-2006 crown with a 3-0 win over Manchester United but then having to lead a guard of honour to the men from Old Trafford as they celebrated winning the championship last season at Stamford Bridge.
The sides have met twice already during the current campaign, with United enjoying success in both matches.
They triumphed on penalties to win the Community Shield in August after a 1-1 draw at Wembley and then, in Grant's first game in charge, Louis Saha and Carlos Tevez gave United a 2-0 victory at Old Trafford.
Will Grant (left) or Ferguson be smiling after Saturday?
This will be the Israeli's first opportunity to properly test himself against Ferguson.
If Grant needs a confidence booster ahead of a clash with the grand master he need only cast his eye at Chelsea's record against United under Roman's rule.
• Before this season United had tasted success against the Blues in the Abramovich era in only one game (November 2005). Chelsea have won six times.
• In cup competitions the Red Devils have fared little better, losing in the FA Cup final last season and the League Cup semi-finals in 2005.
• United have not scored at Stamford Bridge since Abramovich took over - a run of 474 minutes since Ryan Giggs' equaliser in a 2-2 draw back in August 2002.
• Until the 2-0 win in September, United had failed to score more than once against the Blues.
VERDICT: Round two to Chelsea
With seemingly so little between the two sides, and with the stakes so high, Saturday's game could be decided by a piece of magic.
There are plenty of candidates capable of conjuring that killer blow.
Ronaldo and Rooney will be looking to break their duck against Chelsea
United have scored 13 more goals than their rivals and possess the country's runaway top scorer in 28-goal Cristiano Ronaldo, who has 38 in all competitions.
Carlos Tevez (13 goals) and Wayne Rooney (11) have also scored more times than Chelsea's leading marksman Frank Lampard (10).
But there is a glimmer of hope for the challengers.
Rooney and Ronaldo might strike fear into most sides but the Chelsea back line have proved a different proposition.
Ronaldo has yet to find the net in 11 games against Chelsea in a United shirt, while Rooney has failed to register in 15 matches against the Blues for Everton and Manchester United.
On the other hand, Chelsea have plenty of men with match-winning experience in these clashes, in the shape of Didier Drogba, Joe Cole, Ricardo Carvalho and Lampard.
VERDICT: Round three to Manchester United
So Chelsea are the winners on a split decision but even a Blues victory will not see them overtake United at the top on account of the champions' better goal difference.
Saturday 3 May
MAN UTD v West Ham
Monday 5 May
Newcastle v CHELSEA
Sunday 11 May
CHELSEA v Bolton, Wigan v MAN UTD
Chelsea also look to have the tougher task after this weekend, with a trip to in-form Newcastle still awaiting them.
But United have already shown some frailties in their attempts to cross the finish line, dropping points against Middlesbrough and Blackburn .
There is every chance the title could go down to the wire for the first time this century.
All the ingredients are there for a potentially classic ending to the season.
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