Liverpool manager Jurgen Klopp claims Manchester United have "had more penalties in two years than I had in five-and-a-half years".
Klopp hit out at Premier League officials after Monday night's 1-0 defeat to Southampton at St. Mary's.
The Premier League champions have now gone three games without a win and will be back in action on Friday night against Aston Villa in the FA Cup.
After that there's the small matter of Liverpool and Manchester United at Anfield on January 17th and by then United could be ahead of their rivals if they avoid defeat away to Burnley next week.
Klopp was aggrieved his side were not awarded a penalty against Southampton for a challenge by Kyle Walker-Peters challenge on Sadio Mane and the Liverpool boss also thought his side had a case for spot-kick when the ball appeared to hit the arm of Jack Stephens.
Klopp questioned officiating over recent seasons, saying United "had more penalties in two years than I had in five-and-a-half years".
Speaking in his post-match press conference, Klopp said: "We had a really good view of it [the Mane incident], and it looked like a clear penalty.
"I turned around to the fourth official and asked if it was going to be checked, he said it already had been and was not a penalty.
"That's 100 per cent true, and now someone wants to tell me how quick they had it in all these different angles.
"Last year, there was a penalty against Leicester when people said Sadio Mane goes down too easily - if he goes down easily, we would have had a penalty in this game and the last game, a stonewall penalty, but what Andre Marriner did with Sadio Mane I'm not sure if that's okay.
"The boy tried everything, had a few great challenges with Walker-Peters, but there were a lot of situations which should have been free-kicks.
"The last one, when he goes down, you see that back and in the box he hits him in the end with his left foot, that's a penalty.
"We cannot change. I hear now that Manchester United had more penalties in two years than I had in five-and-a-half years. I've no idea if that's my fault, or how that can happen.
"But it's no excuse for the performance. We cannot change it, we have to respect the decisions. But we can change our performance. That's our focus now."
United have been awarded six penalties this season, one more than Liverpool but United were given 14 spot-kicks last season compared to Liverpool's five.
Liverpool have been awarded a total of 30 penalties in 199 league games under Klopp, while United have been awarded 27 in 75 top-flight games under Ole Gunnar Solskjaer.