Arsenal stretched their English Premier League lead to four points when they were gifted a 2-0 home victory over third-placed Southampton on Saturday following a laughable blunder by visiting goalkeeper Artur Boruc.
Southampton, beaten only once previously this season, were holding their own at the Emirates until Polish international Boruc tried to dummy his way past Olivier Giroud in the 22nd minute and was dispossessed by the Frenchman, who scored.
Arsenal, who completed the win through Giroud's late penalty, have 28 points. Liverpool are second on 24 after a pulsating Merseyside derby ended 3-3 at Goodison Park as Daniel Sturridge scored in the 89th minute for the visitors after Everton had twice come from behind to lead 3-2.
The day's London derby was much more Straightforward as Frank Lampard scored twice in Chelsea's comfortable 3-0 win at his old club West Ham United which also took them to 24 points. Southampton are fourth on 22, a point ahead of Everton.
Newcastle United continued their good run with a 2-1 home win over Norwich City to move to 20 points alongside champions Manchester United and Tottenham Hotspur, who are both in action on Sunday at Cardiff City and Manchester City respectively.
Arsenal hit the post twice in the early stages at the Emirates, once via an audacious flick by Aaron Ramsey, but they were handed their opener on a plate.
Boruc had the ball at his feet with plenty of time to clear but twice tried to dummy his way past Giroud, only to lose the ball and give the Frenchman an open goal.
Arsenal's own Polish keeper Wojciech Szczesny had to be on his toes to deny Jay Rodriguez and Adam Lallana as Southampton continued to take the game to their hosts, playing with confidence that showed how far they have come since losing the corresponding fixture last season 6-1.
The game was settled four minutes from time, though, when Jose Fonte grabbed Per Mertesacker as the big defender tried to rise for a header and Giroud buried the penalty for his 10th goal of the season.
Having lost to Manchester United in their previous game before the international break it was an important win for Arsenal, seeking to win the championship for the first time since 2004.
"We have a long way to go (for the title) but we have ambition and the desire is there," said manager Arsene Wenger.
Everton and Liverpool served up a lunchtime classic at Goodison Park, which even by Merseyside derby standards was a humdinger.
On-loan Belgium striker Romelu Lukaku thought he had won it when he headed his second of the match to put Everton ahead after 82 minutes, only for substitute Sturridge to snatch a point for the visitors.
"That is the best experience I've ever had in club football," said Lukaku, echoing the feelings of those lucky enough to watch the pulsating match.
It was end to end stuff from the start as Philippe Coutinho scrambled Liverpool ahead after five minutes, Kevin Mirallas - lucky to escape a red card for a wild challenge on Luis Suarez - equalised two minutes later and a Suarez free kick put Liverpool ahead at the break
Lukaku's second-half double looked to have earned Everton only their second win in 14 derbies until Sturridge levelled.
"I've been involved in a few (derbies) and they are real heart-stoppers," said Liverpool manager Brendan Rodgers. "All-in-all a wonderful game."
Chelsea, with only one point from their last two matches, were making little progress against West Ham in the opening 20 minutes until Jussi Jaaskelainen brought down Oscar and Lampard smashed in the penalty
Neat work by Eden Hazard set up Oscar to calmly finish for the second after 34 minutes and the match was effectively over.
Struggling West Ham fought hard after the break but were finished off eight minutes from time when Lampard swept in his second from the edge of the box.
Crystal Palace climbed off the bottom and above Sunderland after collecting their first away points of the season with a 1-0 victory at Hull City, with Tony Pulis, confirmed as their manager earlier on Saturday, watching from the stands.
Sunderland, who had former England defender Wes Brown harshly sent off in the first half, lost 2-0 at Stoke City, while Martin Jol's woes continued as Fulham slumped to a fourth successive defeat, 2-1 at home to Swansea City.
Image: Olivier Giroud (left) scores the first goal for Arsenal after dispossessing Southampton's goalkeeper Artur Boruc.
Photograph: Dylan Martinez/Reuters