Gareth Bale's superb strike earned Tottenham victory over 10-man West Brom at the Hawthorns - and closed the gap to third-placed Chelsea to one point in the Barclays Premier League.
The Wales international struck his 11th league goal of the campaign mid-way through the second half to end a run of three successive draws for Andre Villas-Boas' team.
Albion played the final 42 minutes with 10 men after defender Goran Popov was sent off for spitting in the direction of Spurs defender Kyle Walker.
Tottenham took full advantage of their numerical advantage to dominate the second period despite the loss of leading scorer Jermain Defoe with an ankle injury.
Bale was a constant threat with his pace and power as he followed up his mid-week equaliser at Norwich with another crucial goal.
Popov's red card was the last thing Albion would have unwanted after all the controversy surrounding striker Peter Odemwingie's aborted move to QPR.
Odemwingie was not part of Albion's matchday squad but it did not stop the Tottenham fans chanting a series of taunts aimed at the Nigeria international.
But of more concern to head coach Steve Clarke will be the fact they have now won only two of their last 14 games in all competitions.
The first half chance fell to Albion after Lukaku's flick header found the recalled Shane Long in space and with only Hugo Lloris to beat.
But his first touch was heavy and forced him out wide and he eventually overran the ball which went harmlessly out of play.
Lukaku was causing plenty of problems and the on-loan Chelsea striker forced a low save out of Lloris after good play by Baggies skipper Chris Brunt.
West Brom goalkeeper Ben Foster came quickly off his line to hack the ball away from Jermain Defoe after he had anticipated a through pass from Gareth Bale.
Lloris pulled off a fine save to prevent the home side going ahead after 20 minutes.
Graham Dorrans threaded a pass through the Tottenham rearguard to Long who took the ball in his stride and raced into the box.
But Lloris was equal to the situation and blocked the resulting shot from the Republic of Ireland international.
Bale was posing the biggest threat to Albion and one 60-yard run ended with a menacing centre which flew across the face of goal.
Defoe, in front of England head coach Roy Hodgson, needed touchline treatment after landing awkwardly on his left ankle when avoiding a challenge from Long.
But he was unable to continue and was helped down the tunnel by two Spurs physios and replaced by transfer window signing Lewis Holtby.
Lukaku shot over from a narrow angle and in first-half injury time Foster tipped a dipping effort from Bale over the bar.
Albion were reduced to 10 men after only three minutes of the second half.
Replays showed that Popov spat in the direction of Spurs defender Kyle Walker after the two had squared up to each other.
Referee Marc Clattenburg instantly brandished a red card at the on-loan Dynamo Kiev left-back.
Albion responded by bringing on a natural replacement for Popov in Liam Ridgewell but they were forced to sacrifice Lukaku upfront.
It was now one-way traffic towards the Albion goal and Foster turned aside a low drive from Holtby.
The former England international was also alert in blocking a close-range attempt from Bale.
But after 68 minutes a stunning strike from Bale put Tottenham in front.
The winger, playing in a more central role, received a pass from Walker, brushed off the challenge of Brunt and his 20 yard shot flew past the despairing dive of Foster into the top corner of the net.
Baggies defender Jonas Olsson then appeared to make a one-fingered gesture towards a section of Albion fans who had jeered a mistake by the Sweden international.
Foster did well to block Clint Dempsey's shot as Spurs searched for the second goal but one proved enough as they secured a valuable away win.