Manchester United have joined Manchester City at the top of the Premier League table after beating Everton 4-0 at Old Trafford.
In the other game overnight, Arsenal produced a vastly-improved away performance to have the better of a 0-0 draw with Premier League champions Chelsea at Stamford Bridge.
Until the 83rd minute at Old Trafford, Everton manager Ronald Koeman must have thought his side had turned an important corner, before a late capitulation left them in the Premier League relegation zone.
Everton were trailing 1-0 to United's Antonio Valencia's early stunner but playing well and threatening an equaliser.
Then Ashley Williams gifted United a second goal scored by Henrikh Mkhitaryan and the floor gave way on Everton.
To rub salt into the wounds, Romelu Lukaku, who joined United from Everton for $139 million in July, made it 3-0, appearing to enjoy kicking his old side when they were down.
Anthony Martial's injury-time penalty completed the rout, meaning Everton have conceded 10 goals without scoring in eight days.
Everton have lost their last four games and have not won since beating Hajduk Split in the Europa League on Aug. 17.
Meanwhile, Arsene Wenger's Arsenal had the better of their 0-0 draw with Chelsea at Stamford Bridge.
Coming off the back of a 4-0 capitulation at Liverpool in their last away game, Arsenal showed far more steel and hit the post through Aaron Ramsey as well as having Shkodran Mustafi's headed goal disallowed.
Tempers frayed near the end with Chelsea's David Luiz shown a red card for a wild tackle on Sead Kolasinac -- their third red card of the season from only five league games.
Arsenal's draw snapped a five-match losing streak away to Chelsea in the league and left them in 12th place with seven points. Chelsea are third with 10 points.
"It was about mentality and a response from our last away game. We could have won it. It was an intense game," Wenger said. "The battle was total.
"We were focused and determined. We tried to play when we had the ball and we were close to winning the game. With a bit more freedom we would have won the game."