Dallas Cowboys head coach Jason Garrett leaves the field after a preseason NFL football game against the Miami Dolphins, Wednesday, Aug. 29, 2012, in Arlington, Texas. The Cowboys won 30-13. (AP Photo/Sharon Ellman)

IRVING, Texas (AP) — Ryan Cook was playing against the Dallas Cowboys in their preseason finale only a couple of weeks ago.

Now he’s their starting center going into second game of the season.

Coach Jason Garrett says Cook has proven he can learn things quickly and did a good job in the season opener at the New York Giants.

Two days after playing for Miami to end the preseason, Cook was traded to Dallas. When Phil Costa had to leave the opener after one series because of back issues, Cook took over at center — and will start Sunday at Seattle.

Cook is in his seventh NFL season, including five with Minnesota before going to Miami last fall. He has started 40 games, but just one at center.

Copyright 2012 The Associated Press.