Context: Hoping to rebound from their loss to the Jets, the Texans flew to LP Field for a Week 2 divisional battle with the Tennessee Titans.  Houston would trail early in the first quarter as Titans running back Chris Johnson got a 57-yard touchdown run.  The Texans would respond with quarterback Matt Schaub completing a 19-yard touchdown pass to wide receiver Andre Johnson, but Tennessee replied with quarterback Kerry Collins completing a 69-yard touchdown to Johnson.  The Titans would add onto their lead in the second quarter as Collins completed an 8-yard touchdown pass to wide receiver Nate Washington.  Afterwards, Houston would take the lead as Schaub completed a 72-yard touchdown pass to Johnson and a 29-yard touchdown pass to wide receiver Jacoby Jones, along with kicker Kris Brown making a 38-yard field goal.  Tennessee would tie the game to end the half as kicker Rob Bironas made a 40-yard field goal. In the third quarter, the Titans got their lead again as Johnson got a 91-yard touchdown run.  Afterwards, the Texans would tie the game as Schaub completed a 1-yard touchdown pass to tight end Owen Daniels.  In the fourth quarter, Houston would take the lead as Brown nailed a 23-yard field goal.  Afterwards, the defense prevented Tennessee from rallying. With the win, the Texans improved to 1-1.  It was the first road win against Tennessee since 2004.

Question: How many yards was the longest touchdown run?

Answer:
91