The Red Devils are currently 12 points clear at the top of the table and have a better goal difference than Manchester City in second spot.
However, despite the fact that his side have a commanding advantage, Rafael has insisted that the team must remain "focused" between now and the end of the campaign.
"We just have to stay focused and play as we have been doing," the Brazilian told MUTV. "We know what happened last year but we have a lot of experienced players here so we'll look to keep improving and keep playing well.
"[Sunday] was a very important win. Everyone talked about us losing the title against Everton last season, so we all worked hard to beat them. It was good to keep a clean sheet but the most important thing at this stage is the points."
Next up for United is a Champions League tie against Real Madrid on Wednesday night.