Luiz Felipe Scolari's men were top of the table on goal difference from Liverpool, with Manchester United trailing eight points behind with a game in hand.
Arsenal proved a turning point with Robin van Persie (now injured) scoring twice in the 2-1 defeat at Stamford Bridge on November 30. Brazilian Scolari was shown the door in February and the championship went to United.
Sunday's big match at the Emirates Stadium sees Carlo Ancelotti's Chelsea back at the top and looking even more irresistible.
United are five points adrift, and Arsenal are a further three behind with a match in hand after ending a 14-match unbeaten run with a 1-0 defeat at Sunderland last weekend.
Injury-troubled Liverpool, who play a Merseyside derby at Everton on Sunday, are seventh and fighting to stay among English soccer's big four after going out of the Champions League in midweek.
Chelsea, already safely through to the last 16 of the Champions League, have now embarked on a series of away games that could prove the key to their season while testing the credentials of their rivals.
After Arsenal, they must travel to Manchester City.
"I really do think we are close to getting back to the invincible feeling we had three years ago," defender John Terry, who made his 300th appearance as club captain against Porto on Wednesday, told British newspaper reporters.
SPECIAL YEAR
"I listen to the other players when we are away with England and they are all talking about how well we're playing. They're fearing us again," he added.
"Now is the time we can pull away...this can be another special year in the history of Chelsea and the next few weeks can move us towards our goal. We are getting close to being dominant."
Like Arsenal, Chelsea have come unstuck away from home this season. They lost at Wigan Athletic, themselves thrashed 9-1 by Tottenham Hotspur in North London last Sunday, and Aston Villa.
Terry said they had learnt from a year ago, however.
"We started well and then threw it away over the Christmas period," he said. "It's just about regrouping, keeping everyone fit and believing."
While Arsenal need to win to put the brake on Chelsea, who won 4-1 at the Emirates last season, Liverpool are desperate for success.
"It's important that we go to Everton on Sunday, try to get the three points and get ourselves back to the top four as soon as possible," captain Steven Gerrard told the Liverpool website.
"Now that we've got the majority of the squad back fit, I'm very confident we can turn things around and go on a long run of winning games."
Manchester United should cut Chelsea's lead to two points on Saturday when they travel to bottom club Portsmouth, who parted with manager Paul Hart on Tuesday.
Fourth placed Tottenham Hotspur can leapfrog Arsenal, at least for a day, when they vis
