"I wouldn't give them up for dead," Vilanova told a news conference previewing Saturday's match at home to Athletic Bilbao, which kicks off a couple of hours before the Madrid derby between Real and Atletico at the Bernabeu.
Unbeaten Barca lead on 37 points, three ahead of resurgent Atletico on 34, with Real, who suffered a third defeat of the campaign at Real Betis last weekend, eight behind their city neighbours on 26.
"We are talking about maybe being 14 points ahead [of Real] after tomorrow but maybe we'll end the weekend only eight in front," Vilanova added.
Vilanova and his players will set a record for the best start to a league campaign if they beat Bilbao after they equalled Real's mark from the 1991/92 season with last weekend's 4-0 win at Levante.
Bilbao, runners-up in the Europa League and the King's Cup last season, have struggled this term and are down in 14th with only four victories to their name.
"It's not normal that we win all our matches," said Vilanova, who stepped up from assistant coach to replace Pep Guardiola at the end of last season. "We should prepare ourselves for when we lose."
Barca's World Player of the Year Lionel Messi has another record in his sights on Saturday.
The Argentine forward is only three short of Gerd Muller's tally of 85 goals in a calendar year set in 1972 and has Saturday's game and a possible six matches more in which to overhaul the German.
