The Patriots opened the regular season at home against the Buffalo Bills. On the very first play of the game, quarterback Tom Brady was sacked by Bills linebacker Takeo Spikes, causing a fumble, which was recovered and returned as a five-yard touchdown to put the Bills ahead to an early lead. New England would tie the game with a nine-yard Brady touchdown pass to wide receiver Troy Brown, but the Bills re-took the lead a 53-yard field goal by Bills kicker Rian Lindell and an 18-yard touchdown run from running back Anthony Thomas.  Despite their first half struggles, the Patriots would win after a 17-yard pass to running back Kevin Faulk, a 14-yard field goal by rookie kicker Stephen Gostkowski, and a safety by defensive end Ty Warren on quarterback J. P. Losman to secure a 19-17 Patriots victory. The win was the 100th of Bill Belichick's career.
Question: Which team was leading at halftime?
Answer: the Bills