According to Ladbrokes, the Wolves manager’s price to get the axe has fallen from 16/1 to 12/1 after he made 10 changes to the side that beat high flying Tottenham Hotspur 1-0 last Saturday.
Wolves' starting XI at Old Trafford had made just 44 appearances between them this season, and were comprehensively beaten 3-0 against an under-strength United side.
And Ladbrokes spokesman Nick Weinberg said: "McCarthy’s decision has only heaped more pressure on him.
"Just when it appeared he was turning the corner following a good win at Spurs."
Phil Brown is still favourite for the chop at 7/4 with Liverpool’s Rafa Benitez in second place at 6/1.
Wolves took 3,400 fans to Old Trafford hoping to see their side pull off another shock against an injury-hit United, only to be left frustrated and disappointed with McCarthy’s team selection.
Arthur Williams, head of the North-West Wolves association told the BBC:
"It's well catalogued that United haven't the best of defences at the moment, with injuries and so on, and I just thought with the likes of the players that were missing we just might have pressed on and got something out of it.
"Wolves sold out their allocation, paid £42 each, plus the time and cost of travelling, and my first reaction when I saw 10 changes and players playing out of position was, I thought, grossly disrespectful."
McCarthy could face punishment for his actions after Premier League chiefs asked for the Wolves manager to explain his team selection.
Under Premier League rule 20, section E, a team must field a full-strength side in all top-flight matches.
