Chelsea staged a remarkable comeback to beat Tottenham Hotspur 4-3 and move four points behind Premier League leaders Liverpool but Arsenal dropped points in the title race on Sunday.
Enzo Maresca's Chelsea side were 2-0 down after 11 minutes at their London rivals but hit back in thrilling style with the instrumental Cole Palmer scoring twice from the penalty spot.
Chelsea's fourth successive Premier League win lifted them to second place with 31 points from 15 games.
Liverpool, whose derby at Everton on Sunday was postponed because of high winds, have 35 points from 14 games.
Arsenal have 29 points from 15 games as they were left frustrated by a late Bukayo Saka goal being disallowed in their 1-1 draw earlier in the day at Fulham.
Bournemouth staged a 2-1 comeback win to deny Ipswich Town their first home victory and Leicester City also came from two goals down to draw 2-2 with Brighton & Hove Albion.
Maresca has talked down Chelsea's title chances but his free-scoring side are now part of the conversation having banged in a league-leading 35 goals so far this season.
"2-0 down, it was the worst picture for us. We conceded two goals from (Marc) Cucurella and a couple more chances from the wrong build-up," Maresca said. "Second half, we deserve to win."
Spaniard Cucurella made an almost comical start to the derby, losing his footing twice under no real pressure and twice being punished with Dominic Solanke and Dejan Kulusevski both scoring to give the hosts a dream start.
But once Jadon Sancho rifled in a shot after 17 minutes to reduce the deficit a wide-open game began to swing Chelsea's way. Palmer equalised from the spot on the hour and was heavily involved again as Enzo Fernandez volleyed Chelsea in front after 73 minutes from the edge of the area.
'Painful one'
Palmer put the icing on the cake with a cheeky 'Panenka' penalty after he had been brought down in the area. Son Heung-min's stoppage-time goal was only a consolation for Tottenham who are down in 11th place in the table.
"It is a sore one, a painful one," Tottenham manager Ange Postecoglou said. "We had moments to get our third and at halftime we were in a decent position. The second half is a ding dong, especially at the start."
With Liverpool falling foul of the elements and fourth-placed Manchester City only drawing on Saturday, Arsenal had the opportunity to make up ground but were stunned when Raul Jimenez gave Fulham an 11th-minute lead at Craven Cottage.
William Saliba equalised from close range shortly after the interval and Arsenal thought they had won it in the 88th minute when Saka headed in, but the goal was ruled out by VAR.
"We dominated most of the game... It's frustrating not to win," Arsenal captain Martin Odegaard told Sky Sports. "We have to focus on ourselves. We don't care about the other teams (in the title race). It's a very long way to go. We've said hundreds of times we have to keep going game by game."
Fulham, who also thwarted the Gunners both home and away last season, have lost just one of their last seven league games and are in 10th place.
Bournemouth climbed to eighth in the table after goals from substitutes Enes Unal and Dango Ouattara propelled them to victory over Ipswich, who are four points adrift of the safety zone in 18th place.
Ipswich took the lead in the 21st minute when Conor Chaplin side-footed home and seemed set for three morale-boosting points until Unal headed home in the 87th minute. Ouattara then grabbed the winner in the fifth minute of stoppage time.
"You start to think it's not your day but luckily we took them in the end," Bournemouth boss Andoni Iraola told the BBC. "The subs gave us the end product that we were missing. We were arriving in the right places but just not finishing."
Late goals by captain Jamie Vardy and Bobby De Cordova-Reid salvaged Leicester City's draw with Brighton at the King Power Stadium. Tariq Lamptey gave the visitors the lead in the 37th minute with a spectacular left-footed strike before Yankuba Minteh doubled Brighton's advantage in the 79th.
Vardy pulled one back seven minutes later before De Cordova-Reid levelled in added time.
Brighton are seventh in the table and promoted Leicester are five points above the drop zone in 16th.
-Reuters