Chelsea manager Jose Mourinho threatened to walk out of his media conference as he bristled at questions about a melee involving Branislav Ivanovic in the 1-0 win over Everton.
Mourinho, who also broke off a BBC interview when asked about the incident, refused to give his view when questioned in the post-match press conference.
Defender Ivanovic appeared to head-butt Everton's James McCarthy in a scuffle before Willian's 89th-minute winner preserved Chelsea's seven-point Premier League lead.
"I am concerned with my reaction because one more question and I leave," Mourinho said, seemingly referencing his recent £25,000 ($38,000, 34,500 euros) FA fine for bringing the game into dispute over the conspiracy claims.
Retrospective action by the Football Association is now a possibility, with Everton manager Roberto Martinez, who lost Gareth Barry to a late red card, strongly critical of the Serbian defender.
Chelsea have already fallen foul of the video replay panel, with striker Diego Costa missing Wednesday's game due to his three-game suspension for stamping on Liverpool's Emre Can in last month's League Cup semi-final.
The Ivanovic incident came directly after referee Jonathan Moss had shown a second yellow card to Barry for a foul on Willian.
Martinez was adamant the official had missed a more serious offence as players from both sides came together angrily in the aftermath of Barry's challenge.
"From that moment the red card gives an unfair momentum to the home side and allows them to score a goal. And then, if you look at the images, Ivanovic's behaviour is wrong. That shouldn't be allowed," Martinez said.
He added: "First of all he grabs James McCarthy around his neck in a very forceful manner. Then he put his head against him. James McCarthy never reacted one single bit and if you want to be fair with the laws, that's a red card.
"It is even more hurtful because Ivanovic was involved in the goal and there was a deflection on the way in and it went through Darron Gibson's legs."
- 'Super' Cech -
Despite the incident, it was a vital win for Chelsea after second-placed Manchester City's 4-1 victory at Stoke, and kept Mourinho on course for a third Premier League crown with the club.
"I don't remember a team becoming champions without a couple of victories in the last minute," he said. "In my case, for sure. Every time I won a league title I had a couple of matches where we won in the last minute.
"This was the first time this season. It was a very difficult match and a difficult Everton. When I say that, it is a compliment. They defended very well, so I am happy with the points."
Mourinho's decision to drop goalkeeper Thibaut Courtois and reinstate Petr Cech also paid off as the veteran pulled off two high-quality saves to deny Romelu Lukaku, the striker Everton signed from Chelsea last year.
"In the first half he made a very good save and in the second, a super one. This is what we need. The goalkeeper can make a difference," Mourinho said.
Martinez agreed that Cech's saves had been crucial in what he called a "cruel" result.
"Petr Cech's reflexes, especially in the second half, was the difference in the scoreline," he said.
"You can lose against Chelsea -- they are one of the best teams in Europe -- but to go down to a very fortunate goal really hurts."
(For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)