Las Vegas sets 49ers as 4 1/2-point Super Bowl favourite The Baltimore Ravens will attempt to pull off a third consecutive upset when they face the San Francisco 49ers in XLVII. According to VegasInsider.com, the 49ers opened as a five-point favourite, but the line was quickly bet down to 4 1/2 points at several major legal sports books. Favourites have gone 8-2 in the playoffs this season (straight up), with Baltimore scoring the only two wins. The Ravens came from behind, forced overtime and beat the Denver Broncos 38-35 in double overtime last week. On Sunday, Baltimore went into New England and beat the Patriots 28-13. Denver was a nine-point favorite, and New England was an eight-point favourite. The over-under for the Super Bowl opened at 49 points, then fell to 48.5. VegasInsider.com reported that favourites are 7-3 against the spread during the postseason.