In week 2, the Lions flew west to play the San Francisco 49ers on Sunday Night Football. The 49ers got on the board first with a 21-yard touchdown pass from Alex Smith to Vernon Davis. The Lions responded with two field goals by Jason Hanson, from 38 and 41 yards respectively. The only scoring play of the second quarter was a 1-yard touchdown run by Frank Gore. In the third quarter came a pair of field goals, first a 36-yard kick by San Francisco's David Akers, and later a 40-yard one from Detroit's Jason Hanson. In the final quarter, both teams kicked two more field goals both from 48 yards out, first the 49ers' David Akers, then the Lions' Jason Hanson. Next, San Francisco's Vernon Davis caught his second touchdown pass of the game, this one from 23 yards out. Lastly, Detroit scored their only touchdown of the game when Brandon Pettigrew caught a 9-yard pass from Matthew Stafford dropping the team to 1-1.

Answer this question based on the article: How many touchdowns did Detroit score?
1