The Giants and Bucs were confronted with winds greater than 40&#160;mph at the Meadowlands, but the Giants' defense dominated early and often.  The Giants were able to hold the Bucs to six three and outs in their first seven possessions.  On offense, Eli Manning and Tiki Barber were effective if not spectacular.  Near the end of the first quarter, the Giants started a 54-yard drive, culminating on a seven-yard touchdown pass from Manning to Plaxico Burress. Midway through the second quarter, the defense struck again as Cadillac Williams fumbled a pitch and tackle Fred Robbins recovered for New York at the Bucs' 28.  The Giants then used a deep pass to Burress and hard-nosed running to extend their lead to 14-0.  The touchdown was scored on a one yard plunge by Brandon Jacobs.  Tampa Bay had chances to get back into the game over the next 20 minutes, but several dropped passes and questionable fourth down plays doomed them.  Overall, rookie quarterback Bruce Gradkowski played well for Tampa Bay, but it wasn't enough.  The Giants clinched the win late in the fourth quarter with some power running from Jacobs and Barber.  Jay Feely added a 31-yard field goal to provide the final points in the 17-3 win. Rookie defensive end Mathias Kiwanuka had his first ever sack and six tackles, middle linebacker Reggie Torbor added a sack, and Fred Robbins continued his fine season with the fumble recovery.  On offense, Barber and Jacobs rushed for over 100 yards combined, Burress notched seven receptions,  and Manning completed 16 of 31 passes for 154 yards and the touchdown to Burress.  The key was his ability to avoid the mistakes in the blustery conditions. Note: The two offensive touchdowns scored by the Giants in this game were the first two offensive touchdowns scored against the Bucs since Tiki and Ronde Barber met for the first time during the 1997 season.
Answer this question: How many of Manning's passes were incomplete?
15