Jose Mourinho hailed a "fantastic" performance from Marcus Rashford as Manchester United blew the Premier League title race wide open with a 2-0 victory over leaders Chelsea.
Goals at the start of either half from Rashford and Ander Herrera condemned Mourinho's former side to their second defeat in four games.
The Blues' lead over second-placed Tottenham is now down to four points with six games remaining, while United boosted their own hopes of reaching the top four by extending their unbeaten league run to 22 games.
The Red Devils are four points behind fourth-placed Manchester City, with a trip to the Etihad Stadium on the horizon on April 27.
Mourinho, though, praised the performance of 19-year-old forward Rashford and his team-mates for a dominant Old Trafford showing.
United boss Mourinho said of Rashford: "He played fantastically well, I think he did also a very good game at Stamford Bridge in the FA Cup.
"Today he scored and it was at the beginning of the match which gave the team confidence and stability. The kid played fantastically well, but everybody fought and did what they had to do."
Mourinho set his team up in a similar way when United fell to a 1-0 defeat at Stamford Bridge in the FA Cup last month after being reduced to 10 men following Herrera's red card.
Referencing that quarter-final clash, Mourinho said: "That game was totally controlled when we played with 11 players, and only the decision that made us play with 10 players gave Chelsea a chance to be dominant.
"We knew that playing this way would be very difficult for them."
Chelsea boss Antonio Conte blamed himself for the defeat, claiming he failed to motivate his players for the clash.
The Italian said: "I think they deserved to win. They showed more desire than us and more motivation, but in this case the fault is with the coach.
"In this case I wasn't able to transfer the right motivation to play this type of game."
Chelsea have a favourable run-in but Conte is wary having dropped points in recent weeks, including a costly slip-up at home to Crystal Palace at the beginning of April.
He added: "I am concerned, we have to work together and find quickly the right desire and ambition to win this title.
"For us it is a fantastic target. For me if we were able to reach this target it would be a miracle. We must understand this and find the right motivation.
"We stay in a great position, but Tottenham are in good form and playing very well and with enthusiasm. We must have the same."
United were ahead on seven minutes after Herrera had split the Chelsea defence with a perfect pass to Rashford, who swept home past Asmir Begovic.
Controversy preceded the goal as replays suggested the midfielder had handled the ball in the build-up, but Herrera protested his innocence.
Herrera said: "I didn't want to touch the ball with my hand. I was running with my arms next to my body and I don't know if the ball touched my arm or not ,but it was not my intention.
"In football, I think if you do not have the intention to touch the ball and you have your arms in a natural position it is not a handball."
Herrera was deployed by Mourinho to man-mark Chelsea playmaker Eden Hazard and did a sterling job throughout.
The Spain international also contributed by doubling United's advantage with a deflected strike just four minutes after half-time.
Herrera said of the team's performance: "It was almost perfect. Defensively it was perfect, they didn't create any chances, and on the counter-attack we hurt them. We can be very happy."
Rashford added: "We're a team, just missing one player it doesn't cancel out everything that we've worked on throughout the week."