Darren Fletcher is aware the Premier League title will not be handed to Manchester United on a plate.
The Red Devils are currently in pole position but lost their 29-match unbeaten record at Wolves last weekend.
Despite that setback, Sir Alex Ferguson's men are four points clear of second-placed Arsenal and five in front of Saturday's derby-day opponents Manchester City with 13 matches remaining.
However, Scotland midfielder Fletcher knows his side cannot afford to take anything for granted as they bid to secure a record 19th crown.
"You have got to earn the title," he said.
"Nobody gives you the trophy. The team that wins the league will be the team that deserved it and showed the best form throughout the season.
"That is always said and hopefully we can prove our title credentials in the next few months."
Fletcher has acknowledged the importance of United's visit of City at the weekend, and is aware the significance of the fixture goes way beyond local pride.
"This is when the big games come that can ultimately win you trophies," said Fletcher.
"We've got to go to Liverpool and Arsenal, still play Chelsea twice and we have Manchester City this weekend.
"But we enjoy big games. This club is all about performing and rising to challenges.
"We know they lie ahead of us. We're not naively thinking that the league is over."
United are still competing on three fronts this season, with UEFA Champions League and FA Cup success also on their radar.
But Fletcher insists there is no complacency within the side, adding: "I am not saying we are going to win the treble, but we are still in all competitions and looking well.
"We are in a good position in the league but by no means are we taking that for granted.
"We are looking to kick on and keep winning these matches.
"The Premier League has shown that it is getting even more competitive.
"There have been so many shock results this season. We have to be wary of that and make sure we go into every game in top form."