Substitute Edin Dzeko scored twice in the last 10 minutes — his second coming in injury time — to earn City a 2-1 victory at West Bromwich Albion despite playing with 10 men for more than an hour.
Second-place Manchester United remained level on points with City thanks to a 4-2 home win over Stoke, with Wayne Rooney scoring twice — as well as an own goal — to open his account for the season.
Chelsea, though, looks unstoppable at the moment after recovering from going 2-1 down to end Spurs' four-match winning run under former manager Andre Villas-Boas.
Spain playmaker Juan Mata grabbed two goals and set up another for the unbeaten visitors, who have picked up 22 points from a possible 24 this campaign — matching City's start to its title-winning season last year.
"There are 30 games still to play," Chelsea manager Roberto di Matteo said. "(The win) makes us a team that is strong and makes our start even better, but with 30 more games I still think that you have to wait until the Christmas period."
Arsenal dropped further off the pace by surprisingly losing 1-0 at Norwich, which picked up its first win of the season, and Raheem Sterling became Liverpool's second youngest scorer ever in the Premier League by grabbing a first-half winner in the 1-0 victory over Reading at Anfield.
The win was only the hosts' third at home in 2012, lifting them up to mid-table.
West Ham maintained its impressive start to life back in the top division by thrashing Southampton 4-1, while Swansea beat Wigan 2-1 and Fulham edged past Aston Villa 1-0.
The standout match came at White Hart Lane, where Villas-Boas was undone by a player he signed in the summer of 2011 when in charge of Chelsea.
Mata engineered a turnaround for the visitors after early second-half goals by William Gallas and Jermain Defoe had cancelled out the lead given to Chelsea by Gary Cahill's spectacular volley. Cahill was playing in place of John Terry, who began a four-match suspension for racially abusing an opponent last October.
Mata equalized in the 66th with a low drive then curled in a fine finish three minutes later to reclaim the lead for Chelsea, who clinched victory through substitute Daniel Sturridge — a goal set up by the effervescent Mata.
"We signed Mata for his talent and he is certainly not going to stop producing these moments of brilliance like he had today," Villas-Boas said.
Chelsea's seventh win in eight games leaves the team comfortably clear of the Manchester clubs, who achieved wins in contrasting ways on another high-scoring day in the Premier League.
While City left it late to remain the only other team — after Chelsea — yet to be defeated, United relied on its powerful forward line to get past Stoke at Old Trafford.
Rooney nodded into his own net in the 11th but the England striker, fresh off scoring three times for England over the past week, scored either side of goals by Robin van Persie and Danny Welbeck. Rooney's second was his 200th club goal while Van Persie moved to eight goals for the season in all competitions.
"Most of the games at home this season, we've had terrible starts," said United manager Alex Ferguson. "When we did get going, we played some terrific football."
Ferguson was later highly critical of defender Rio Ferdinand for failing to wear a T-shirt before the match that promoted the Kick It Out anti-racism campaign. Ferdinand chose not to don the top out of protest at a perceived lack of action by the campaign group in recent high-profile racism cases.
James Milner was sent off for City in the 23rd minute for a professional foul on Shane Long, who put West Brom ahead in the 67th minute at the Hawthorns.
Dzeko was introduced in the 79th, equalized a minute later by heading home Carlos Tevez's free kick and then steered home the winner in the second minute of stoppage time.
"It was tremendous how we stuck together in the second half and created so many chances," City assistant manager David Platt said. "It's a great fillip to win after playing for almost 70 minutes with 10 men."
Grant Holt snatched Norwich's winner over a lacklustre Arsenal, which is now 10 points behind Chelsea.
West Ham scored all its goals in the second half against Southampton, with Mark Noble (two), Kevin Nolan and Modibo Maiga on target.
Pablo Hernandez and Michu were the scorers for Swansea, ending the team's five-match winless run in the league, while Chris Baird's 84th-minute goal earned Fulham victory against Villa.