A number of furious Chelsea players surrounded the referee after they were denied a spectacular stoppage-time winner against Aston Villa.
Axel Disasi thought he had netted the winning goal at Villa Park after heading the ball beyond Robin Olsen to complete a dramatic comeback and put the Blues 3-2 in front.
However, as the Chelsea players returned from celebrating with the travelling supporters, referee Craig Pawson was urged to go over by VAR and look at his pitch-side monitor for an incident leading up to the goal.
Benoit Badiashile appeared to shove Diego Carlos in the back as the ball was dropping into the box, before it was crossed into Disasi to head home from close range.
Although the incident looked soft, Pawson decided it was enough for a foul to be given and the goal was chalked off. The Chelsea players seemed perplexed at the decision, while Villa were relieved.
Neither side could force a winner in the remaining couple of minutes as both had to settle for a 2-2 draw, which dents the Blues' hopes of qualifying for Europe this season.
After the full time whistle, Chelsea expressed their frustration at the officials for controversially disallowing their winning strike. Several players, including Noni Madueke, Disasi and Madueke surrounded Pawson, while Pochettino stormed on to the pitch to help separate the protests.
Pochettino was then spotted having a brief conversation with Villa defender Ezri Konsa as tempers seemed to calm down. Understandably, the Blues were annoyed after coming from behind to spark a dramatic comeback and playing superbly during the second period in the West Midlands.
Speaking after the game, Madueke felt the goal should have counted. He said: "Should it have been three points? Yes. Do I think the goal should have stood? Yes. Nothing else to say about the situation.
"We need to play better at times in phases of the game. We have an abundance of quality and when we fire we're a match for any team. The last game was terrible. For 70 minutes today the team were outstanding.
"It's a process. I'm proud of the team today. We beat them here earlier in the season as well. We wanted to come here and win but it wasn't to be."
Meanwhile, Pochettino told TNT Sports: "Everyone that was watching the game will feel disappointed. Two different things the referee said it was a foul and disallowed the goal and then going to the VAR to confirm.
"The referee is unbelievable and it's ridiculous. It is difficult to accept, these type of things in the semi-final [ FA Cup against Man City] two weeks ago it was handball and it was no penalty, the referee he didn't check it.
"It is painful as it has damaged English football and I think Villa players and their fans didn't understand why the goal was disallowed.
"They said it was foul and if you see the challenge what happened if we go into every single challenge like this it is going to be a foul and we wouldn't finish the game with 11 [players]."
Villa went 2-0 ahead during the first half through a Marc Cucurella own-goal and another fine strike from Morgan Rodgers, and looked set to earn their third successive Premier League victory. However, Chelsea came back and pulled one back through Madueke, before Gallagher levelled in the 81st minute.
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