Arsenal moved a step closer to the Premier League title as Max Dowman became the competition's youngest-ever goalscorer in a dramatic 2-0 win against Everton, while Chelsea's top-four bid was dented by a 1-0 defeat against Newcastle on Saturday.
Mikel Arteta's side struggled to break down obdurate Everton until the closing moments at the Emirates Stadium.
But Sweden forward Viktor Gyokeres finally found a way through in the 89th minute, with a helping hand from Everton goalkeeper Jordan Pickford.
Pickford completely missed Dowman's cross, and Piero Hincapie bundled the ball back into the six-yard box for Gyokeres to tap into the empty net.
The ensuing scenes of delirium on the pitch and in the stands underlined the significance of Arsenal's fourth successive league win.
There was still time for Dowman to run the length of the pitch and slot home with Pickford nowhere to be seen after coming up for an Everton corner that ended in a rapid Arsenal counter-attack in the final seconds.
Dowman, aged just 16, is the youngest scorer in the history of the Premier League, as well as Arsenal's youngest scorer.
The Gunners are now 10 points ahead of second-placed Manchester City, who face West Ham at the London Stadium in the day's late kick-off.
Arsenal, trophyless since 2020, are hunting a first English title in 22 years.
The quadruple chasers rode their luck to beat Everton despite a disjointed performance, adding to the mounting feeling that they will be one of the least stylistically impressive champions in recent memory if they do take the crown.
But Arteta and company won't care about that ahead of a huge week.
The Gunners have a Champions League last-16 second leg against Bayer Leverkusen next week, with the tie level at 1-1, before heading to Wembley to face City in the League Cup final.
Arsenal don't play in the league again until April 11 when they meet Bournemouth.
CHELSEA ROCKED
City's clash with West Ham is the first of their two games in hand on Arsenal, with Pep Guardiola's men also hosting the leaders in April.
City must bounce back from their midweek Champions League last-16 first-leg defeat at Real Madrid in a match of significance at both ends of the table.
West Ham sit in the relegation zone but can leapfrog Nottingham Forest and Tottenham with a victory over City.
Fifth-placed Chelsea were beaten by Anthony Gordon's goal at Stamford Bridge to round off a painful week.
Thrashed 5-2 at Paris Saint-Germain in the last-16 first leg, Liam Rosenior's side were breached in the 18th minute when Tino Livramento's pass allowed Joe Willock to burst clear and tee up Gordon for a composed finish.
Chelsea trail Aston Villa and Manchester United by three points having played a game more than their top-four rivals.
Brighton beat Sunderland 1-0 to climb into the top half of the Premier League, while second-bottom Burnley held Bournemouth in a 0-0 draw.
Sunderland were unbeaten in their first 11 home games back in the top flight but have now lost their last three at the Stadium of Light to slip to 12th.
Yankuba Minteh scored the only goal when his shot somehow squeezed past goalkeeper Melker Ellborg at his near post.
Brighton move above the Black Cats on goal difference and into 10th.
The stalemate at Turf Moor did little for either side as Burnley slip closer to relegation and Bournemouth failed to move in on the European places.
The Clarets are eight points adrift of safety with eight games remaining.
Bournemouth remain in ninth, three points behind Brentford in what is likely to be the final European spot in seventh.