When Manchester City and Chelsea square up at Eastlands on Saturday lunchtime both sides will feel they have a point to prove.
For free-spending City, a win against the champions would reignite talk of a title challenge. It would also be their third league sacking of Carlo Ancelloti's men in as many meetings - no mean feat when you consider Chelsea have lost just six of their last 43 Premier League games.
All six of those defeats came last season, of course. As we stand in this campaign Chelsea have won five from five, scored 21 times and conceded just once. To say they've hit the ground running is like saying Didier Drogba is a pretty handy player.
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Chelsea's best ever start to a season is under threat. Jose Mourinho was at the helm when they started the 2005/06 campaign with nine wins and a draw, and they went on to win the title at a canter from Manchester United.
But not everybody is convinced this vintage is as Special. Chelsea's victims so far this season have been West Brom (6-0), Wigan (6-0), Stoke (2-0), West Ham (3-1) and Blackpool (4-0) - five of the six leading bookies' favourites for relegation.
All of which has made it obligatory to bill Saturday's trip to face City as 'Chelsea's first real test'. Win, and they'll win the league. Lose, and they're an aging outfit who'll fade away at the end of the season and be begging for the return of Mourinho come May.
Carling Cup injuries to Salomon Kalou, Yossi Beyayoun and Gael Kakatu have naturally fuelled the doubters, putting Ancelotti in the bizarre position of having to defend a side who've absolutely battered all Premier League comers this season.
Of course in reality we all know that's short-sighted hyperbole. But while Saturday's result will not define either club's campaign - it's still the biggest game of the season so far; more relevant the Manchester United v Liverpool by a country mile. It's a glimpse at what could be the future axis of power at the Premier League's top table.
Chelsea are already there. Three titles in six seasons and never worst than third in the last seven tells us that. And while some still pine for Mourinho, Ancelotti has his haul of two titles in his sights and a genuine shot at ending their Champions League drought this season.
City are a work in progress, but with such enormous financial weight behind them it's hard to envisage a Premier League title not arriving at Eastlands inside the next three-five seasons.
Meanwhile, Liverpool are in financial meltdown and Manchester United look a diluted version of the dominant side that won three successive titles between 2006 and 2009. As for Arsenal, the suspicion remains that unless Arsene Wenger's transfer policy changes the title will remain just beyond their reach.
All of which points towards Chelsea and Manchester City building towards a rivalry that could define the Premier League title race for a decade - a rivalry that could yet start in earnest this season.