West Ham United's hopes of avoiding relegation suffered a cruel blow as an own goal by midfielder Tomas Soucek and Harry Kane's first goal since December condemned them to a 2-0 defeat at Tottenham Hotspur on Tuesday.
The visitors were fortunate just before halftime when VAR ruled out Son Heung-min's goal for offside, but their luck deserted them after the break at an empty Tottenham Stadium.
West Ham responded well and Jarrod Bowen was denied an equaliser by the upright before Kane was played through on goal by Son's pass and beat Fabianski with a trademark finish.
Defeat left West Ham above the relegation zone on goal difference from Bournemouth who have a game in hand.
West Ham manager David Moyes said his side were better than in the 2-0 defeat by Wolverhampton Wanderers at the weekend and was convinced Tottenham's opening goal should have been ruled out.
"I've only just seen it, and I can't believe they've ruled that as a goal. Any handball is disallowed? That's the rule. Who is on VAR tonight? Not very good eh?," he told Sky Sports.
Tottenham's first win in eight matches in all competitions kept them in the hunt for a Champions League qualification berth. Jose Mourinho's side are seventh with 45 points, one behind fifth-placed Manchester United.
Mourinho's first game in charge after taking over from Mauricio Pochettino was a 3-2 away win at West Ham in November.
The atmosphere that day was in marked contrast to Tuesday's behind-closed-doors return, although the stakes were massive for both clubs for different reasons.
No wins in four Premier League games had seen Tottenham overtaken in the battle to qualify for the Champions League while four defeats in five Premier League games had left West Ham in serious danger of relegation.
Yet the first half of what is usually a feisty derby was devoid of goalmouth incident until just before halftime when Son cut in and arrowed a low shot past Fabianski, but had strayed marginally offside when receiving the ball.
Heartened, West Ham started the second half well and Pablo Fornals wasted their best chance early, scuffing wide when unmarked in front of goal.
It proved a decisive moment as Soucek's blunder sent West Ham on the way to a seventh successive away Premier League defeat for the first time since 2006.