The Steelers traveled to London, England and were considered the visitor team against a Matt Cassel-led Vikings team.  The Vikes got off to a fast start as Blair Walsh nailed a 54-yard field goal for a 3-0 lead followed up by Matt Cassel hooking up with Greg Jennings on a 70-yard touchdown pass for a 10-0 lead.  The Steelers managed to get on the board later on in the first quarter when rookie RB Le'Von Bell ran for an 8-yard touchdown to make the game 10-7.  The Vikes moved ahead by double digits in the second quarter as Adrian Peterson ran for a 60-yard touchdown for a 17-7 lead.  Shaun Suisham got the Steelers within a touchdown by nailing a 26-yard field goal for a 17-10 lead.  Walsh moved the Vikes ahead by 10 at halftime by kicking a 37-yard field goal for a 20-10 lead.  The Steelers came within 3 as Le'Von Bell ran for a 1-yard touchdown shortening the lead to 20-17 but the Vikes managed to move ahead 27-17 after Peterson ran for a 7-yard touchdown and then Cassel found Jennings again on a 16-yard touchdown pass to make the lead 34-17.  In the 4th quarter, Jerricho Cotchery hooked up with Ben Roethlisberger on a 15-yard touchdown pass for a 34-24 lead, and then tried to rally as Suisham nailed a 28-yard field goal.  The Steelers' comeback attempt was ruined again as Roethlisberger was sacked and fumbled the ball with less than a minute left in the game sealing the victory for the Vikes. With this loss, the Steelers are off to their worst start since the AFL-NFL merger. They had last started 0-4 in 1968, when they started 0-6.  This is also the first time since 2006 in which the team would fall to 4 games below .500 when they started that season 2-6.

Answer this question based on the article: How many rushing touchdowns did Adrian Peterson have?
2