Manchester City sit 15 points clear of second-placed United going into today’s matches.
Yesterday, Jose Mourinho admitted City were uncatchable and his side would now be battling to finish second with 13 games of the season left.
He said: “We need to try to finish second - we have been in this position all season. First for a few weeks, but we have been second for the rest.
"It has been better than last season in every aspect - points, position, number of goals, goals conceded - everything.
"We have to try to stay there and it is not easy because there are some very good teams. Chelsea are the champions, Arsenal did well in the market, Liverpool are a great team and Tottenham are fantastic.”
But Lukaku insists he hasn’t given up on winning a first Premier League trophy with anything still possible.
"Of course it is good everything is stable," Lukaku told Sky Sports when discussing Mourinho signing a new contract.
"He can continue building on what he is building now. Everybody knows how the manager works.
"If we do everything right until the end of the season, add in some reinforcements in the summer, we will be even stronger than we are now.
"I do not think the same as the manager. It [the league] is not done yet, we have to keep fighting."
City can extend their lead over United to 18 points with victory at Burnley in the early kick-off today.
But United will have the chance to close the gap once again when they host Huddersfield at 3pm.