Gary Neville has called on Romelu Lukaku to prove he can fire Manchester United to the title with a match-winning performance against Liverpool .
The Belgian has scored seven goals in as many Premier League games since his £75million move from Everton this summer.
But Neville believes it is in games like this afternoon's that he will ultimately be judged.
He said: "What he's done so far is what he's supposed to do, turning draws into wins. This is where he will define himself as a great striker, in the big games.
"This is where United become champions or not. This is where he has to deliver. Of course there has to be a debate [over whether he is world class], but he's done everything he has been asked of so far."
United are currently second in the league, behind neighbours and rivals Manchester City.