Sam Allardyce believes Manchester City's Yaya Toure should have been sent off before his team took the lead in their 3-0 FA Cup victory at Crystal Palace.
Fine goals from Raheem Sterling, Leroy Sane and Toure earned City a place in the competition's fifth round and the margin of victory their impressive performance deserved.
David Silva was particularly influential as they outclassed their relegation-threatened hosts at Selhurst Park, but Allardyce remained frustrated that referee Mike Jones did not give Toure a second yellow card for his first-half challenge on Jordon Mutch.
The foul appeared only routine, and resulted in Palace being awarded an attacking free-kick, but when asked if he felt City could have been down to 10 men, Allardyce said: "You mean should have been down to 10 men? Yeah.
"They should have been down. Mutch had been booked for much less. That was a sending off, so the referee hasn't done his job.
"On the consistency of what the referee was doing, (that) was a certain yellow card. But I've got more to worry about (with) the players, and goals we conceded, than referees at the moment.
"We've lost the habit of winning. We recovered from a sticky start, worked our way into the game, had a couple of half chances, and then conceded that soft goal just before half-time."
Defeat means Palace have only Premier League survival to concentrate on and leaves Allardyce with only one win from eight since his appointment. Even that came against League One Bolton in a third-round replay, and to worsen the manager's concerns, new signing Jeffrey Schlupp suffered a hamstring injury.
"Schlupp's a big blow, he'll be missing for a while," said the 62-year-old. "(And the signing of Sunderland's Patrick van Aanholt is) close but I'm not absolutely certain it's finished yet. Hopefully he'll be involved on Tuesday (at Bournemouth).
"I've no idea what the situation is with Andros (Townsend) other than that Steve (Parish) the chairman has not told me Newcastle have made any type of bid whatsoever for us to consider. So that's not even in the back of my mind."
The positivity surrounding City's performance and their progress to the fifth round was furthered by their captain Vincent Kompany completing 90 minutes on his first senior appearance since November.
Sergio Aguero missed out because of a knock which could yet rule him out of Wednesday's Premier League fixture at West Ham and which led to Gabriel Jesus making his full debut.
There is also the matter of the FA Cup beginning to look like City's best chance of winning a trophy this season, but their manager Pep Guardiola is refusing to make it a priority.
"(Kompany) was injured a long time, and every time he came back he couldn't finish 90 minutes," said the Spaniard, 46. "He was injured (on and off) for two years but the doctors and physios did an exceptional job. His willingness to keep going, it's very important for us.
"(Aguero) had a problem and against Tottenham (last week) felt something in his back. We have four days until Wednesday so we're going to see his condition during the week.
"(The FA Cup) is important to all Premier League teams. The Champions League is the sweetest one, but in England, the Premier League is the most important, the second one is the Cup. Of course it's important."