The Reds let an eight-point lead slip in the table in 2011/2012, crucially allowing Manchester City to move top with a 1-0 win the derby ahead of winning their final two fixtures with Newcastle and QPR.
It means United are not getting carried away with a 15-point advantage this time around, even if many pundits are already referring to Sir Alex's side as champions-elect ahead of the trip to Sunderland.
"We didn't expect this situation, at this stage of the season, with nine games left," said Vidic. "No-one expected that but we are happy with it. Especially the way it went in this league, even last year, we were eight points clear and we dropped the points.
"That is why there are so many points this year and people are still saying 'are you sure you are going to win the title'. You are never sure until you have the trophy in your hands. We are 15 points clear but we still have big games to play. I keep saying that. I know people are saying we have the title already but we have to play Chelsea, West Brom, Swansea etc. They are teams who can hurt you. They are tough games. Teams who are fighting relegation. We just have to keep winning.
"We have reacted well this season. We trained hard and we got into the situation we are in now. We are in charge of the title. We are going to Sunderland, we are not bothered whether they celebrated or not last year. We are going to play our game and try to get the three points, which is important for us. We want to be 15 points clear before we play Manchester City. It is a big game for them but it is a big game for us as well