That is the verdict of Starsport columnist Paul Merson, who reckons Rashford’s pace is the only weapon Manchester United have that could trouble Pep Guardiola’s men.
Manchester City have won ten league games in a row going into Wednesday’s Manchester derby. But they lost to a Tottenham team inspired by Heung-Min Son in the Champions League.
And former Arsenal great Merson, who won the league twice with the Gunners, claims Rashford will have to cause them similar problems if City are to slip up.
But Merson reckons United will have to raise their game massively if they are take any points off their rivals after losing so badly at Everton.
He told Starsport: “Marcus Rashford is so quick and we saw how City’s back four didn’t like it when Son ran at them with pace.
“Rashford is going to be United’s danger man in the derby. I don’t see how else they can hurt City. They need to get him running at defenders one-on-one.
“He might be the only one can stop them, because I can see City winning every game until the end of the season now.
“It’s so tight at the top between City and Liverpool that whoever drops any points from now on is probably going to miss out on the championship.
“But City going out of the Champions League just makes it even more likely they will win the title because they have no other distractions now.
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“They will be playing less games with no big midweek European matches to occupy them and they will be able to get more rest and stay fresher.
“Form goes out of the window in a derby, but unless Manchester United improve dramatically I can’t see them taking points off City. Rashford’s pace is the only thing that could trouble them.”
England star Rashford has scored 16 goals so far this season for club and country but he hasn’t hit the target yet in four games this month.
And United warmed up for the derby in the worst way possible – with a 4-0 thrashing at Everton which has left them sweating on a top-four finish.
Merson said: “People might think that could help United. That they will have to respond and put up more of a fight. But they are a million miles off City for me.
“If City show up and play the way they have been for the last few weeks they will win the game. It’s all in their hands.
“City can change their team and it won’t get any weaker. That’s a massive luxury to have. And if they win this game the title is theirs to lose really. Liverpool have done well just to stay with them.”