The Premier League’s most unpredictable title race has produced another surprise as Chelsea lost at Crystal Palace for the first time since 1990.
John Terry headed Joel Ward’s cross into his own goal at the start of the second half to gift Palace a 1-0 victory, leaving Chelsea’s position at the top precarious.
Chelsea’s second successive away loss gave Manchester City a chance to go top later in the day by beating Arsenal.
Putting the pressure on City, Chelsea manager Jose Mourinho is publicly writing off Chelsea’s prospects of lifting the trophy.
“We depend too much on other results,” Mourinho said.
“When you depend a little it’s possible, when you depend a lot, I don’t think it’s possible.
“We depend now too much. I don’t think now we can win the league.”
But Palace’s chances of staying in the league have been enhanced, with the south London club five points clear of the drop zone following the derby triumph.
There was also a shock at Old Trafford: Manchester United won easily.
After back-to-back losses at home, seventh-place United came from behind to beat Aston Villa 4-1, with Wayne Rooney scoring twice.
Southampton, a place behind United but six points adrift, produced a resounding 4-0 victory over Newcastle.
In a meeting of relegation-threatened teams, both West Bromwich Albion and Cardiff scored in stoppage time as they drew 3-3.
Stoke’s impressive form continued with Peter Odemwingie clinching a 1-0 victory over Hull, the team’s fourth success in five matches.
Swansea climbed above Hull into 13th by ending a six-game winless run in the league. Jonathan de Guzman’s clinical double and Wayne Routledge’s goal produced a 3-0 victory over fellow struggler Norwich.