The Belgium international moved to Manchester United in a £75m deal from their Premier League rivals Everton last summer.
Lukaku scored 10 goals in his opening nine games in all competitions to reassure Manchester United supporters of his quality.
However, the 24-year-old required another 29 games to net his next 10 goals to raise some questions marks about the summer signing.
Lukaku’s hold up play has been a source of criticism from some pundits, including ex-Everton midfielder Kevin Kilbane.
However, the Belgian forward has impressed in recent weeks with goals against Manchester United and Crystal Palace.
The summer signing has netted 14 times in 28 games in the Premier League this term, creating six goals for his team-mates.
Lukaku, though, believes he has proven himself to be an unselfish player for Manchester United boss Jose Mourinho throughout his first campaign at Old Trafford.
“I think the work rate I am delivering to the team is a lot and he knows he can come to me whenever,” Lukaku told Sky Sports.
“I will always put the team first ahead of myself and that’s something I told him, I said ‘the team is the most important thing’.
“The desire to win is bigger than ever since I came to this club, because I always wanted to win and to chase trophies. I always put that in front of my personal objectives and he knows that, and I think that’s the reason why I’m playing all the time.”
Lukaku has netted four times in seven games in the Champions League to help the Red Devils reach the Champions League last 16.
Manchester United finished in sixth place in the Premier League last term but won the Europa League and the League Cup.
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