Beginning a stretch of three straight home games, the Patriots faced off against the 9-3 Steelers in their first afternoon game in five weeks. Before the game, Steelers safety Anthony Smith guaranteed a win for the Steelers. After going three-and-out on their first drive, the Patriots fell behind 3-0 early on a 23-yard Jeff Reed field goal to cap an 8-minute, 15-play Steelers possession. A 39-yard Chad Jackson kickoff return gave the Patriots the ball at their own 48-yard line to begin a 9-play drive that ended in a 4-yard Moss touchdown catch to give the Patriots the lead. Moss' touchdown catch was his 18th of the season, surpassing Curtis Martin for the Patriots' record for touchdowns by a single player in a season. After a Steelers three-and-out the Patriots, on their first offensive play of the second quarter, increased their lead to 14-3 on a 63-yard play action pass from Brady to Moss. A 30-yard Willie Parker run on the Steelers' ensuing series set up a 32-yard touchdown pass from Ben Roethlisberger to Najeh Davenport. After a Patriots drive in which a muffed punt recovery by Pittsburgh led to a missed 48-yard field goal attempt by Gostkowski, the Steelers mounted a 12-play drive that lasted almost 6&#160;minutes before a 44-yard Reed field goal cut the Patriots' lead to 14-13. With 2:29 left in the half, a 32-yard Gaffney reception helped the Patriots drive to the Steelers' 24-yard line; after two Brady incompletions Gostkowski kicked a 42-yard Gostkowski field goal, giving the Patriots a 17-13 lead at halftime. On the Patriots' first drive of the second half, on 1st and 10 from their own 44-yard line, after a Brady lateral pass to Moss fell short, Moss picked it up and threw it back to Brady, who then found Gaffney deep for a 56-yard touchdown. After another Steelers three-and-out, the Patriots' second possession of the half also went for a touchdown, as a 2-yard Welker reception capped a 10-play drive that included one run, a 4-yard Brady scramble. In the opening minutes of the fourth quarter, the Steelers moved the ball to the Patriots' 1-yard line, but failed to score on 3rd and goal and 4th and goal. The Patriots took the ball at their own 1-yard line and then began a 6-minute, 12 play drive, passing on every down. Using a no-huddle offense, Welker caught five straight passes to bring the Patriots to the Steelers' 36-yard line. Brady completed four more passes to set up first-and-goal from the Steelers' 10-yard line, but his next three passes were all incomplete, leading to a 28-yard Gostkowski field goal. The Steelers' next possession, a 13-play drive, ended in another failed fourth down conversion. After a Patriots punt, the Steelers ran the ball three times to give the Patriots their 13th win of the season; with the win, the Patriots improved to 13-0 and also clinched a first-round playoff bye.
Question: How many points were the Patriots leading by at the half?
Answer: 4