Chelsea rallies back, tops Tottenham
A comprehensive away win looked on the cards as the Blues dominated a poor Spurs team in the first half, taking the lead through a fine Gary Cahill volley.
Villas-Boas, sacked by Chelsea 226 days ago after a dismal eight-months in charge, inspired a turnaround in his team's fortunes in the second half as Spurs surged ahead through William Gallas and Jermain Defoe, before the Blues stunned their former manager with two goals nearly 20 minutes from the end.
Much has been made of the impact of Eden Hazard and Oscar since they arrived this summer, but it was Mata, signed by Villas-Boas last season, who settled the game with two clinical strikes.
The Spaniard scored his fifth of the season after pouncing on another poor Gallas clearance, and then made it 3-2 soon after with a clever finish from Hazard's pass.
Roberto Di Matteo, Villas-Boas' right-hand man last season, then punched the air with glee when Daniel Sturridge made it 4-2.
Villas-Boas had claimed personal vengeance was not a motivation for him in the run-up to this game, and he did not look crestfallen at the final whistle.
Yet the Portuguese, who turned 35 this week, must be hurting inside after seeing his team blow an opportunity to tear up Chelsea's unbeaten run and show Roman Abramovich he was wrong to cut short his "project" at the Stamford Bridge.
It was all smiles for the former Chelsea boss at the kick-off. He shared handshakes and hugs with the Chelsea staff after emerging from the tunnel, but his smile soon disappeared.
Chelsea started strongly and took the lead in the 17th minute when Gallas' poor header fell straight in to the path of Cahill, who fired a bullet volley beyond Brad Friedel from 12 yards.
Petr Cech did well to parry a low Defoe drive but Spurs were poor and both Lennon and Defoe were wasteful in front of goal.
Gylfi Sigurdsson offered a brief glimmer of hope when he shot a yard wide - but Chelsea should have doubled their lead moments later when Mata picked up a rebound from his original shot at Friedel, but he skied well over from 10 yards.
Tottenham started to lose their discipline, with Gallas and Kyle Walker both seeing yellow for rash challenges.
However, the hosts started the second half brightly and they leveled within 65 seconds of the restart when Jan Vertonghen hooked Tom Huddlestone's free-kick across the box and Gallas nodded in from one yard.
Spurs looked a totally different side to the one that waded slowly through the first half, launching wave after wave of flying attack.
Sigurdsson tested Cech with a powerful shot and saw another deflected effort fly just over.
Villas-Boas remained calm, but he was soon off his bench punching the air again when Defoe snuck in between two defenders to clip the ball past Cech from Lennon's pass. It was his 200th career goal.
Cole thought he should have had a penalty when he went down under pressure from Gallas, but the referee waved play on.
Spurs threw everything at the visitors, but they could not beat Cech again and Chelsea made them pay with two crucial goals from Mata in two minutes.
First the Spaniard latched on to Gallas' poor clearance to beat Friedel and he then lost the Tottenham defender soon after to latch on to Hazard's pass and make it 3-2.
"That's why we're champions" shouted the fans of the Chelsea team whose victory in Munich denied Tottenham a place in the Champions League last year.
Only a top save from Friedel prevented the Spaniard completing his hat-trick moments later.
Villas-Boas looked to Emmanuel Adebayor for inspiration, the marksman coming on for Dempsey with 17 minutes left.
The former Arsenal man made an immediate impact, nodding the ball to Sigurdsson, but despite some excellent skill, the Iceland international could only shoot over.
Torres curled a chance to put the game to bed wide with four minutes left and Adebayor stabbed at a chance soon after when Cech spilled the ball, but the Chelsea stopper smothered the ball.
Sturridge, a late replacement for Oscar, made the points safe in the 91st minute - and the away fans taunted "Andre, what's the score?"