Jose Mourinho maintained his hold over Arsene Wenger with leaders Chelsea enjoying a routine 2-0 win over Arsenal on Sunday after the two old adversaries became involved in an ugly touchline spat.
Wenger could face disciplinary action after shoving Mourinho in the chest midway through the first half after a heated exchange of views.
It was Mourinho, once again, who had the last laugh though with goals from Eden Hazard and Diego Costa securing a win to stretch Chelsea's lead at the top to five points.
Mourinho is yet to taste defeat when up against Wenger, winning seven and drawing five of their clashes.
Chelsea were not at their best but for all Arsenal's possession they rarely looked like replying once Hazard had earned and converted a 27th minute spot kick.
Costa continues his scoring spree for Chelsea
The hosts appeared content to sit back in the second half until former Arsenal skipper Cesc Fabregas, up against his old club for the first time since returning to the Premier League from Barcelona, sent Costa clear with 12 minutes remaining to wrap up the points.
Costa had been quiet throughout but took his tally to nine league goals in seven matches for the Blues.
The only worry for Chelsea was a first-half head injury to keeper Thibaut Courtois who soldiered on for a while before being replaced by Petr Cech.
After a 15-minute delay caused by an incident with a flare outside the stadium, the opening half proved a feisty affair.
Arsenal began in confident fashion with Alexis Sanchez having the first shot in anger.
The Chilean was in the thick of the action minutes later when stretching to reach a Jack Wilshere through ball he accidentally clattered into Courtois.
Sanchez was then on the receiving end of a hefty challenge from Gary Cahill that had Wenger incensed and storming into Mourinho's technical area.
Wenger was lucky to escape punishment from the referee
When Mourinho confronted the Frenchman, Wenger offered a two-handed shove into the chest of the Portuguese who last season described his rival as a "specialist in failure".
Wenger was lucky to escape punishment from the referee but the incident raised the decibel level in the stadium and appeared to spark the hosts into life.
Shortly after a still groggy Courtois was helped off, Chelsea took the lead.
Hazard's swerving run was ended abruptly by Laurent Koscielny for a penalty that the Belgian fired into the bottom left corner.
Arsenal playmaker Mesut Ozil flitted in and out of the game and ironic home cheers greeted one tackle on the German by Fabregas who displayed calm authority throughout an often tetchy afternoon.
Hazard was impressive
Chelsea went close to extending their lead after the break when Hazard's low cross was almost sliced into his own goal by Mathieu Flamini.
The fleet-footed Hazard became increasingly influential, giving young left back Calum Chambers some anxious moments.
Any hope Arsenal had of salvaging a point were dashed, however, when Fabregas, perhaps lucky not to concede a penalty earlier when he blocked Wilshere's shot with his arm, lofted a ball forward for Costa to race clear and lob Wojciech Szczesny.
Van Gaal grateful to De Gea as United go fourth
Radamel Falcao grabbed his first goal for Manchester United to secure a 2-1 Premier League victory over Everton on Sunday.
It put United fourth in the table on 11 points, five behind leaders Chelsea, who host Arsenal in one of three other games on Sunday.
United manager Louis van Gaal was able to celebrate a second successive victory for the first time since taking charge in the close-season, but as in the recent 2-1 win over West Ham United, his team almost threw two points away at the end.
Van Gaal admitted being grateful to goalkeeper David De Gea for a series of fine saves, including one from Leighton Baines's penalty and then three more in the last few minutes.
"When you hold a penalty and then hold three magnificent saves in the dying seconds, then you are great because you win the game," the manager said.
Di Maria opened the scoring for United
He also praised Angel Di Maria, who scored the first goal and contributed the assist for Falcao's winner but added: "It's strange because every time the first half is very good and then the second half is so different."
Argentina international Di Maria scored his third goal in four games to give United the lead in the 27th minute but Baines, after missing a penalty for the first time with his 15th Premier League spot-kick, crossed for Steven Naismith to head an equaliser in the 55th minute.
Colombian striker Falcao, playing in place of United's suspended captain Wayne Rooney, poached the winner in the 62nd minute from a mis-hit shot by Di Maria.
De Gea made three outstanding saves
In the last few minutes De Gea made three outstanding saves, twice from Leon Osman and once from Costa Rican Bryan Oviedo as United's inexperienced defence struggled to hold on. Di Maria suggested that the goalkeeper should have been named man of the match by broadcaster Sky Sports instead of him.
He said he was delighted too for fellow South American Falcao in scoring his first goal for the club, adding: "It's great for him, he's been looking for it for a while and it's very important for him.
"Not only him but the whole team is on the right road now."
Everton were left in the bottom four with their manager Roberto Martinez ruing De Gea's brilliant performance and complaining that the referee should have stopped play before United's second goal because Steven Pienaar was down injured.
"The referee made a major error there," he said. "Our second-half performance deserved more than we got and we finished really strong at the end."
