Champions Manchester United were held to a 0-0 home draw by 10-man Reading and lost England striker Wayne Rooney to a hairline fracture of his left foot in a wretched start to their title defence on Sunday.
Chelsea opened their new Premier League season with a record-breaking 3-2 home win over Birmingham City while Arsenal snatched a late 2-1 victory at home to Fulham.
The injury to Rooney, who suffered a broken bone in his foot in 2004 and 2006, will cast a shadow over United's opening weeks of the season. The fracture, sustained in a challenge by Reading defender Michael Duberry towards the end of the first half, was revealed by a hospital scan.
United did not say how long the 21-year-old would be sidelined, but his absence will also be a major setback for England in their battle to qualify for Euro 2008.
United manager Alex Ferguson was already without fellow-strikers Louis Saha and Ole Gunnar Solskjaer through injury on Sunday. New Argentine signing Carlos Tevez was also missing but will now be expected to shoulder an even bigger burden.
In the game, United had all the possession but failed to make it count against a Reading side who had substitute striker Dave Kitson sent off in the 72nd minute, less than a minute after coming on, for a reckless tackle on Patrice Evra.
"It just wasn't our day," Ferguson told Sky Sports before he knew the extent of the injury.
"We created chances...but we just didn't take one of them."
Chelsea, looking to wrest the title back from United this season, took the points at Stamford Bridge with a second-half strike from Ghana midfielder Michael Essien.
Victory was made even sweeter by Chelsea setting an unbeaten home record in the top flight of 64 games. The run dates back to February 2004 and eclipses the previous mark set by Liverpool from February 1978 to January 1981.
BIG FOUR
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There was no shortage of goals in west London, where Birmingham took a shock lead with a 15th-minute header from Finnish, former Chelsea striker Mikael Forssell.
The hosts hit back with goals from league debutants Claudio Pizarro of Peru and Frenchman Florent Malouda, who was on target again after scoring in last Sunday's Community Shield defeat by United.
City levelled with a left-footed, bullet strike from their new French signing Olivier Kapo, but Essien gave Chelsea a deserved victory with a curling first-time shot from Shaun Wright-Phillips's cut-back.
Chelsea coach Jose Mourinho told BBC radio: "We had so many chances to kill the game, it would have been more enjoyable for me to see a 4-2 or a 5-3 than a 3-2."
GOOD GAME
But he added: "It was a good game to celebrate the home record, a game with goals and enthusiasm, and better than a 0-0 where we still have the record but it's not a good game."
Mourinho, whose side have suffered a spate of injuries, was without captain and central defender John Terry, but was able to send on Ivorian striker Didier Drogba from the subs' bench.
A goalkeeping howler by Arsenal's Jens Lehmann gifted Fulham their first-minute lead, the German's clearance handing Northern Ireland striker David Healy a tap-in on his competitive debut.
But Dutch striker Robin van Persie equalised with an 83rd-minute penalty and Belarus midfielder Alexander Hleb struck a 90th-minute winner.
"Better late than never," Arsenal manager Arsene Wenger told BBC radio after his side's late strikes. "We were physically and mentally strong and didn't give up.
"That kind of result can change a season for a team, and certainly strengthen the belief."