Tottenham's 1-0 loss at home to Fulham had opened the door for Chelsea and they took full advantage by recording a victory that lifted them to within four points of second-place Manchester City.
Lampard broke the deadlock against his former club West Ham in the 19th minute at Stamford Bridge, springing to head Eden Hazard's dinked cross into the top-right corner.
The England midfielder, 34, now stands only two goals behind Bobby Tambling in the list of Chelsea's all-time top goal-scorers.
Hazard added a delightful second goal five minutes into the second half, exchanging passes with Juan Mata on the right and drifting past Winston Reid before drilling a left-foot shot into the bottom-right corner.
"It is a long race. We have to carry on and win our next game and see what others do," said Chelsea interim manager Rafael Benitez.
"In the first half, we could have scored two or three goals and you have to be pleased because we scored two goals and kept a clean sheet."
Fulham dealt Spurs' challenge for a Champions League place another setback by condemning Andre Villas-Boas' side to a second consecutive Premier League defeat.
Having eliminated Inter Milan from the Europa League on Thursday, Spurs were bidding to tighten their grip on third place in the table and Gareth Bale had an early header cleared off the line by Sascha Riether.
However, the hosts lost Michael Dawson to injury at half-time and then saw former striker Dimitar Berbatov claim the game's only goal in the 52nd minute when he converted Riether's low right-wing cross.
Spurs' best chance fell to Jermain Defoe in the dying stages, but his effort from Bale's cut-back met its match in a superb reflex save from Mark Schwarzer.
Coming in the wake of last weekend's 3-2 loss at Liverpool, Spurs' defeat left them a point below Chelsea and four points above fifth-place north London rivals Arsenal, both of whom have a game in hand.
At the other end of the table, Arouna Kone struck in the final minute to give Wigan Athletic a 2-1 win at home to Newcastle United that injected fresh momentum into their quest to escape relegation.
Jean Beausejour's first Wigan goal put Roberto Martinez's men ahead in the 19th minute, but Italian full-back Davide Santon drilled home an equaliser in the 72nd minute.
Then, in the 90th minute, Ivorian striker Kone lashed the ball into the roof of the net following a goalmouth scramble to leave Wigan three points from safety with a game in hand on fourth-bottom Aston Villa.
"It's disappointing we're in this position again and it's up to us to get ourselves out of it," said Wigan midfielder Shaun Maloney.
The game had threatened to be overshadowed by a horrendous, knee-high challenge from Wigan midfielder Callum McManaman on visiting defender Massadio Haidara in the first half.
McManaman escaped punishment for the foul, but Haidara had to be stretchered off and Newcastle coach John Carver was sent to the stands after losing his temper at the half-time whistle.
"The tackle was awful," Newcastle manager Alan Pardew told Sky Sports.
"I lost a game in the last minute to what I think is handball (in the build-up) and I've got a boy who's going to hospital."
Pardew also revealed that referee Mark Halsey had apologised to him for not spotting McManaman's foul.
Earlier, relegation-threatened Sunderland failed to capitalise on the dismissal of Norwich City goalkeeper Mark Bunn as they were held to a 1-1 draw at the Stadium of Light.
After Wes Hoolahan headed Norwich in front in the 26th minute, the visitors lost Bunn to a straight red card when he handled the ball outside his area.
Craig Gardner levelled for Sunderland with a 40th-minute penalty after a handball by Sebastien Bassong, but Sunderland could find no way past the visitors' 10 men in the second half.
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