With their Super Bowl title to defend, the Steelers began their season at home in the annual kickoff game against the Tennessee Titans.  After a scoreless first quarter, Pittsburgh would get their first score of the season as quarterback Ben Roethlisberger completed a 34-yard touchdown pass to Super Bowl XLIII MVP wide receiver Santonio Holmes near the end of the second quarter.  The Titans would respond with quarterback Kerry Collins completing a 14-yard touchdown pass to wide receiver Justin Gage.  Just prior to halftime, pro-bowl safety Troy Polamalu went to the locker room after suffering a knee injury.  He would not return to the field and it would later be revealed that he strained his MCL. After a scoreless third quarter, Tennessee would take the lead in the fourth quarter as kicker Rob Bironas got a 45-yard field goal.  Pittsburgh would tie the game as kicker Jeff Reed made a 32-yard field goal. With time running out, the Steelers drove down the field again, and lost the ball to a rare Hines Ward fumble, allowing the Titans to run the game into overtime. In overtime, the Steelers won the cointoss and never relinquished the ball.  In the end, Pittsburgh emerged victorious as Reed nailed the game-winning 33-yard field goal. This also marked the first time that the Steelers were able to win against Collins.
Question: What made Pittsburgh lose the ball in the fourth quarter?
Answer: a rare Hines Ward fumble