Frank Lampard out-witted Jose Mourinho as Chelsea powered to a 2-0 win at Tottenham on Sunday that featured a double from Willian, a red card for Son Heung-min and allegations of racist abuse.

Billed as a showdown between Mourinho and Lampard, an explosive London derby showed the student is more than a match for the man who served as his mentor during their time together at Chelsea.

Blues boss Lampard pulled a tactical masterstroke as he cleverly changed his team's formation, leaving Tottenham manager Mourinho unable to respond as Willian opened the scoring with a blistering strike and increased Chelsea's lead with a penalty before halftime.

Tottenham's South Korean star Son was sent off for a needless kick at Antonio Rudiger in the second half as Chelsea swept to a sweet victory over their former manager.

With top four rivals Manchester United losing at Watford earlier in the day, it will be a happy festive period for Lampard's fourth placed side, who sit six points clear of seventh placed Tottenham after ending a run of four defeats from their last five Premier League games.

There was little Christmas cheer for Tottenham, who may have to answer for the behaviour of their fans amid claims Rudiger was racially abused and an object was thrown at Chelsea keeper Kepa Arrizabalaga.

A fan was seen directing a 'monkey gesture' at Rudiger and three announcements over the tannoy that "racist behaviour from spectators is interfering with the game" painted a bleak picture of the latest racist incident to scar European football this term.

Lampard had already beaten Mourinho last season when his Derby met the Portuguese coach's Manchester United in the League Cup and once again he proved too smart for his old boss.

After a hug and handshake between Lampard and Mourinho, there was a poignant minute's applause for Tottenham and England World Cup winner Martin Peters, who died aged 76 on Saturday.

Those shows of respect marked the end of the civilities as Tottenham fans booed Marcos Alonso vociferously and chanted about his involvement in a fatal car crash in Spain several years ago.

TACTICAL TWEAK

Chelsea had the perfect response to the cruel taunts as they completely dominated possession in the early stages and took the lead in the 12th minute.

With Tottenham too slow to mark up, Willian took a short corner to Mateo Kovacic and when the Brazilian received the return pass, he adroitly side-stepped Serge Aurier before curling a superb finish into the far corner of Paulo Gazzaniga's net.

There was an extra edge about Willian's celebrations given the abuse of Alonso as he sprinted to pose in front of the Tottenham fans.

Aware of Chelsea's frailties at the back, Lampard had switched to a five-man defence and dropped Jorginho in a move that allowed N'Golo Kante to return to his preferred deep-lying midfield role.

The tactical tweak worked a treat and Tottenham's only decent chance of the entire match was wasted by Harry Kane, who fired over from Moussa Sissoko's cross.

With the supply lines to Kane shut down, Lampard's team deservedly doubled their lead in first half stoppage-time.

To the chagrin of Tottenham's fans, Alonso was the catalyst as he chased a long ball into the penalty area and was clattered by Gazzaniga's desperate rush off his line.

After a VAR review, the spot-kick was awarded, with Willian calmly slotting past Gazzaniga for his fifth goal of an exceptional campaign for the winger.

That made it an alarming 14 goals conceded in all competitions by Tottenham since Mourinho replaced Mauricio Pochettino.

Any hopes of a Tottenham comeback were quashed in the 62nd minute by Son's needless clash with Rudiger.

Falling to the turf after a collision with the Chelsea defender, Son responded by kicking both feet at Rudiger.

A lengthy VAR review led to Son's dismissal for violent conduct, sparking an ugly end to the clash as Tottenham fans appeared to tarnish their club with sick racist taunts at Rudiger.