Tottenham Hotspur's hopes of chasing down Chelsea at the top of the Premier League have been dealt a potentially fatal blow, as they fell to a 1-0 defeat against West Ham United on Friday night.
A close-range finish from Manuel Lanzini 65 minutes in proved the difference in the end, leaving a below-par Spurs side four points adrift of leaders Chelsea, who take on Middlesbrough in their game in hand on Monday.
Back-to-back home wins over London rivals Spurs for the first time in 17 years also eases West Ham's lingering relegation worries, lifting them past the 40-point mark and making it five without defeat for under-fire boss Slaven Bilic.
Matchwinner Lanzini was looking a threat early on for the hosts, getting into dangerous positions on a couple of occasions but dragging wide of the target from the best of those openings.
The first on-goal attempt of the evening arrived 15 minutes in when Cheikhou Kouyate's header was easily dealt with down the middle by Hugo Lloris, who also had to get behind Mark Noble's 25-yard drive later in the half.
Tottenham were far from their best in the opening 45 minutes but will perhaps have felt that they should have taken a lead into the break, having created the best two openings through Harry Kane and Eric Dier.
Kane saw his shot somehow helped over the crossbar by the trailing leg of Adrian, after both his and Dele Alli's initial efforts inside the box were blocked, while Dier's header from the resulting corner was palmed away.
Referee Anthony Taylor was kept busy, handing out three yellow cards for strong tackles in the first half and being given a big decision to make a little over a quarter of the way through when Lloris took out Lanzini outside the box, adjudging that the Frenchman got some of the ball before the player.
Andre Ayew blasted over from the edge of the area and Son Heung-min forced a smart stop out of Adrian as both teams pressed for an opener, but the breakthrough goal did eventually arrive 65 minutes in.
A cross from Aaron Cresswell on the left bounced around in the area and, after falling nicely into the path of Lanzini, the playmaker was never going to miss as he prodded past Lloris and gave West Ham the lead.
It was the Argentine's ninth goal in 14 London derby meetings in the Premier League, which was no doubt celebrated just as wildly in the west part of London by Chelsea supporters.
West Ham were not willing to sit back on their slender lead and should have had a second 15 minutes from time, only for Lloris to produce a superb save to deny Jonathan Calleri from seven yards out.
Christian Eriksen rescued Tottenham at Crystal Palace recently, but there was to be no way through on this occasion as his shot fizzed wide late on to bring an end to the Lilywhites' nine-match winning run, and indeed their outside title hopes.
Chelsea now need two wins from games against Boro, West Bromwich Albion, Watford and Sunderland to make certain of a third top-flight crown in eight years.
