Jan Molby has urged Manchester United to beat Manchester City and do a "massive favour" for Liverpool in helping them keep their top four hopes alive.
Louis van Gaal's side are unbeaten in the last five league games - which includes a 2-1 win over the Reds at Anfield - and they take on their local rivals in the derby clash at Old Trafford this Sunday.
United are third in the table with 62 points from 31 games, one point ahead of City and eight points ahead of fifth place Liverpool. Brendan Rodgers' side take on Newcastle United on Monday and a victory for United and Liverpool will see the latter close the gap to four points for fourth spot.
"Manchester United could do Liverpool a massive favour at Old Trafford on Sunday. If they beat Manchester City and then the Reds get three points against Newcastle on Monday the race for the top four will be back on," Molby told the Liverpool Echo.
Manuel Pellegrini's men are not enjoying a great run away from home. The Premier League champions have managed just one win in the last seven matches played in all competitions and have suffered four consecutive defeats.
With the current form, the former Liverpool striker believes the only way the Merseyside club could finish in the top four only if City suffer further defeats.
"City aren't in great form and things don't look right there. Sunday is a huge game for them. Some teams are used to fighting hard to get in the top four- the likes of Liverpool, Arsenal and Tottenham," the 51-year-old said.
"But City are used to fighting to win titles. I don't know how their players will react if they lose to United and find themselves playing for fourth place. If any of the current top four are going to fall away it will be City. United and Arsenal are in good form and don't look like they are going to be derailed."
"Newcastle were poor against Sunderland and if they perform like that again then Monday will be a great time for Liverpool to play them. John Carver will look to get them fired up. He's fighting for his own future at the moment but it does look like they have raised the white flag and their season is more or less over."
"We need to make a strong start and put Newcastle on the back foot to knock the last bit of motivation out of them," Molby concluded.