Chelsea's recent implosion in the Premier League looks to have set up another two-team race for the title between Manchester United and Manchester City, making Sunday's derby the biggest match of the season so far.
United will travel to the Etihad Stadium holding a three-point lead over the champions, with neither team having hit top form so far.
While City remains unbeaten but yet to show the kind of attacking spark that swept the team to the title last season, United has relied on its star-studded strikeforce to make up for its shaky defending.
United manager Alex Ferguson is so exasperated by his side's defending that he compared it this week to a kids' television program in his native Scotland, "Cartoon Cavalcade."
"It's a worry," said Ferguson, whose team has fallen behind in 15 of its 23 games this season. "If we perform like that on Sunday, then God knows what's going to happen to us."
The emergence of big-spending City - once famously described by Ferguson as "the noisy neighbors" - has rapidly made the Manchester derby arguably the most high-profile match in English football.
Having lost both league matches to City last season - including a humiliating 6-1 defeat at home - United would take great pleasure in ending the only unbeaten record in all four of England's leagues.
"If we win, it will be one of our best-ever results," Ferguson said. "They are a really good, powerful team with massive players."
City can focus its attention on the Premier League after getting knocked out of the Champions League, and not even making the Europa League after losing to Borussia Dortmund 1-0 on Tuesday.
"Clearly this can help us win the Premier League because we don't play in the Europa League," City manager Roberto Mancini said.
When Chelsea beat Tottenham 4-2 on Oct. 20, the team held a four-point lead, was playing free-flowing football and was being talked up as the early title favorite.
However, the European champions haven't won in the league in seven games since, leaving them 10 points behind United in third, and have also seen their title defense in the Champions League come to an end in unprecedentedly quick fashion.
Chelsea can at least point to Wednesday's 6-1 thrashing of FC Nordsjaelland in their final Champions League group match as a sign that things are on the up, with interim manager Rafa Benitez gaining his first victory since replacing the fired Roberto Di Matteo two weeks ago.
The much-maligned Fernando Torres even scored twice, ending his month-long run without a goal.
When asked if it could be a springboard for Torres, Benitez said: "I hope so. He's shown his desire and quality at the same time. If we can play at this level, then I think he can score more goals."
On Saturday, Chelsea visits Sunderland - another club whose manager has been under pressure this season. Martin O'Neill's fast start to his tenure at the northeast club has dried up, with just two wins in the team's last 22 matches.
"We need to stand up and be counted and take our chances," Sunderland midfielder Craig Gardner said. "We can't keep doing this after games, saying, 'It'll come, it'll come.' We need to make it come."
Also Saturday, Arsenal looks to restore confidence after dropping to 10th place in the standings when it hosts West Bromwich Albion, which is fifth following an impressive start to the season. Last-place Queens Park Rangers travels to Wigan seeking a first win of the campaign, while it's also: Aston Villa vs. Stoke; Southampton vs. Reading; and Swansea vs. Norwich.
Liverpool visits West Ham and Everton is at home to fourth-place Tottenham in Sunday's other matches. On Monday, Fulham hosts Newcastle.