The former 13-time League Champions are now placed at the eight position in the table, five points away from all the members of the "big-six" clubs.
Pallister added of another man proven at the very highest level: "I was absolutely buzzing when United signed him because his performances at Arsenal showed he was a world-class talent".
"And so it feels as if it would be Jose Mourinho to go".
Manchester United have reportedly decided not to proceed with plans to appoint a sporting director for the time being, and are not expected to resume the search while Jose Mourinho remains in charge of the club. I saw him as a bit selfish, someone who played for himself sometimes.
United travel to Chelsea this Saturday in the lunch time kick-off, with Mourinho desperate for a good result.
Sarri faces another busy period handling his squad who will be battling for major honours on all fronts.
Manchester United can ill afford to lose more ground on their title rivals Manchester City, Chelsea FC and Liverpool FC, considering the Red Devils are already seven points off the pace.
Ross Barkley may well retain his place ahead of Mateo Kovacic but the rest of the line-up looks set to be quite predictable, especially in comparison to that of United.
Merson added: "If United do lose, the pressure will nearly certainly crank up again on Jose Mourinho".
Marcos Rojo is a long-term absentee with a knee problem.
See how many you can get in our quiz below, and catch the next chapter in the rivalry between Chelsea and Manchester United when they go head to head at Stamford Bridge on Saturday, live on Sky Sports Premier League from 11.30am.
With astute positioning, excellent communication and intelligent defending, United's defenders could look after Hazard by passing responsibility zonally instead of using a man-marker. but if you've seen Man Utd defend in any recent games, you might see why that's wishful thinking.
The left-back was 18 when he joined from Southampton in June 2014 for a fee thought to be £30m, then a record for a teenager. The Blues are second in the table after an unbeaten start to the league season.