LONDON â€” Dele Alli underlined his growing reputation by single-handedly ending Chelsea's 13-match winning run Wednesday, scoring two headed goals to give Tottenham a 2-0 victory over the Premier League leaders.
The defence has been the bedrock of Chelsea's three-month hot streak but Alli was gifted space to score carbon copy goals in each half at White Hart Lane after meeting crosses from Christian Eriksen.
By taking his tally to seven goals in four games, the 20-year-old Alli inflicted Chelsea's first loss since its last trip to north London at Arsenal in September and prevented the Blues from earning a league record 14th successive win in a single season.
"This league is very tough," Chelsea manager Antonio Conte said. "Now it's important to restart. After 13 wins in a row it's difficult to accept defeat."
Chelsea still leads Liverpool by five points but Tottenham is now only seven points behind in third after a fifth successive victory.
"It's a big statement for us but we are happy to stay under the radar," said Alli, whose team's hopes of a first title since 1961 were ended by Chelsea last season.
Conte established the winning run that sent Chelsea to the summit after switching to a three-man defence to stem the tide of goals in a 3-0 first half collapse at Arsenal.
But the defence is now leaking goals, conceding four in the last two matches after only letting in two in the previous 12 fixtures. Tottenham matched Chelsea's formation and restricted Conte's side to few chances, while proving more cohesive and solid at the back to frustrate the visitors' forward line.
"I didn't get on the ball as much as I would have liked to," Alli said.
The midfielder didn't need to.
Alli was described on the eve of the game by manager Mauricio Pochettino as the "most important player to emerge in English football in recent years." Signed from third-tier club MK Dons two years ago for 5 million pounds (then $8 million), Alli lived up to his manager's exalted praise with his mastery of the attacking spaces.
While Chelsea was looking more likely to score on the counterattack in the first half, Tottenham used a break to devastating effect on the stroke of halftime with Alli making the breakthrough.
Kyle Walker teed up Eriksen and as the cross was floated into the penalty area, Alli was left unmarked between Victor Moses and Cesar Azpilicueta to coolly nod past goalkeeper Thibaut Courtois.
It was an assertive start to the second half by Chelsea, but Tottenham preserved its lead.
Goalkeeper Hugo Lloris blocked a low shot from Diego Costa, Eden Hazard's low header was off target and Moses' penalty appeals were dismissed when he was clipped by Mousa Dembele.
Spurs then punished Chelsea's porous defending again in the 54th minute with a replica of the opener.
Walker did the running down the right flank before laying the ball off for Eriksen. The Danish international picked out Alli between Moses and Azpilicueta, and the midfielder found the target with this header.
"We were short of the levels we set ourselves, for whatever reason that may be, a few misplaced passes and not moving the ball as quick as we have been," Chelsea defender Gary Cahill said. "They are a top quality opposition and we got punished for being short."
Chelsea's plight in the derby was summed up in the first half by the team's top scorer, Costa, engaging in an on-pitch row with Pedro Rodriguez for several minutes. It followed Pedro's failure to run into space in front of goal to meet a pass from Costa when the score was still 0-0.
"It is normal disappointment," Conte said. "It was a good chance for us and we wasted it."
Rob Harris is at www.twitter.com/RobHarris and www.facebook.com/RobHarrisReports
Rob Harris, The Associated Press