With Arsenal having snatched a late 1-0 victory over Wolverhampton Wanderers at The Emirates with a header from Nicklas Bendtner deep into stoppage time, just three points separate Chelsea (74 points), United (72) and Arsenal (71).
Bookmakers Ladbrokes installed Chelsea as 6/4 on favourites for the title, followed by United at 12/5 and Arsenal at 9/2 but with all three teams still facing tricky matches before the season ends on May 9, the outcome is far from certain.
Unlike many recent seasons which have developed into a one- or two-horse race, this campaign has bucked that trend with the lead changing hands for the 20th time on Saturday.
Chelsea boss Carlo Ancelotti was naturally delighted with his team's success but played down any title talk after goals from Joe Cole and Didier Drogba, who was offside when he collected the ball before scoring, gave his side the points.
NOT FAVOURITES
Asked if he thought Chelsea were now favourites to win the title, Ancelotti told Sky Sports: "No we are not the favourites.
"We might be top of the league but we have to play five matches and have to pay attention and stay focused and maintain our composure, but nothing is decided yet."
Chelsea, seeking their first championship since back-to-back successes in 2005 and 2006 and eyeing an FA Cup and league double, can gain confidence from one telling statistic.
Saturday's win completed the double over United this season following their 1-0 victory at Stamford Bridge in November.
They also have a 100 percent record against Arsenal and perennial top four finishers Liverpool.
Chelsea beat Arsenal 3-0 at The Emirates and 2-0 at home, and also defeated Liverpool 2-0 at Stamford Bridge.
If they maintain their fine record at Anfield on May 1, their title dream could come closer to reality.
Chelsea's other four games are against Bolton Wanderers at home on April 13, Tottenham Hotspur away on April 17, Stoke City at Stamford Bridge on April 25 - followed by the Liverpool match - and finally Wigan Athletic at home on May 9.
They also face Aston Villa in an FA Cup semi-final next Saturday and, following their 7-1 win over Villa in the League last week, a probable FA Cup final appearance against Spurs or Portsmouth at Wembley Stadium is likely on May 15.
Manchester United, who clearly missed injured England striker Wayne Rooney on Saturday, continue their run-in with a visit to Blackburn Rovers on April 11, followed by the short trip to neighbours Manchester City on April 17.
EASIER FINISH
They then face Spurs at home on April 24 and visit Sunderland on May 1 before wrapping up the season against Stoke City at Old Trafford on May 9.
Arsenal have what looks the easier finish, apart from their next league match at arch-rivals Spurs on April 14. They then visit Wigan on April 18, face Man
