Chelsea enjoyed a timely return to form to outplay Tottenham Hotspur in a 2-0 away victory in the Premier League as Frank Lampard outwitted his former mentor Jose Mourinho in their managerial battle on Sunday.

Willian struck both Chelsea goals in the first half as Chelsea consolidated fourth place while Tottenham’s dismal afternoon went from bad to worse as forward Son Heung-min was shown a red card just past the hour mark.

Chelsea coach Lampard, who won two of his Premier League titles in Mourinho’s first reign at Stamford Bridge, conjured a game plan that allowed his side to dominate from start to finish, aided by a shoddy home performance.

Willian punished some slack defending to open the scoring after 12 minutes and a labouring Tottenham barely created a decent chance in response.

A rush of blood to the head for Tottenham keeper Paulo Gazzaniga gifted Chelsea a penalty, awarded by VAR, just before half-time to put Chelsea in complete control.

Tottenham’s hopes of a revival were scuppered when Son needlessly kicked out at Antonio Rudiger and was shown a red card, with the decision again being made by VAR.

The hosts could also find themselves in hot water after an object was thrown at Chelsea keeper Kepa Arrizabalaga and Rudiger appeared to suggest he had been victim of racial abuse.

Chelsea’s win, after four defeats in their last five Premier League games, means they have tightened their grip on fourth place, opening up a four-point lead over fifth-placed Sheffield United with Tottenham six points back in seventh spot.

It was the first time in 14 matches at home against one of his previous clubs that Mourinho had suffered a defeat.

United shocked

In Watford, a terrible blunder from Manchester United goalkeeper David de Gea helped Premier League basement side Watford to a 2-0 victory for their first home win of the season and maiden victory under coach Nigel Pearson. The Spain keeper, who had conceded a soft goal in last week’s 1-1 draw with Everton, allowed the weakest of shots from Ismaila Sarr through his hands in the 50th minute, putting Watford in front for the first time in a home game this season.

Senegalese winger Sarr was then tripped by United’s usually reliable Aaron Wan-Bissaka and earned the penalty from which Troy Deeney doubled Watford's lead in the 54th minute, sending De Gea the wrong way and blasting into the net.

United, who have failed to build on the momentum from back-to-back wins over Tottenham Hotspur and champions Manchester City earlier this month, produced yet another limp display and failed to hit the target in the first half.

United’s fifth Premier League defeat of the season leaves them eighth on 25 points after 18 games, while Watford are still bottom but level on 12 points with 19th-placed Norwich City.

United manager Ole Gunnar Solskjaer wrote off De Gea’s costly error as a rare error but was scathing about his side's performance.

“It was a mistake, it happens in football and it is what we train for every day to make sure they don't happen again. David has been very good lately. It is just one of those things that happen,” he said.

“We started the game slow. The first half was very, very poor from both sides, it was too slow, like a testimonial. You have to earn every point on the pitch and today we didn't deserve that.”