Answer based on context:

The Cowboys' fourteenth game was an NFC East rivalry rematch against the Redskins at home. In the first quarter the Cowboys took the lead with kicker David Buehler hitting a 42-yard field goal, followed by QB Jon Kitna throwing a 3-yard TD pass to WR Miles Austin; then Buehler made a 20-yard field goal to put Dallas up 13-0. The lead was narrowed when QB Rex Grossman completed a 19-yard TD pass to RB Ryan Torain, but the Cowboys increased their lead with Kitna making a 14-yard TD pass to TE Jason Witten, followed by RB Tashard Choice getting a 3-yard TD run. The Redskins replied with Grossman getting a 10-yard TD pass to WR Santana Moss, but the Cowboys scored again with Buehler got a 20-yard field goal. Washington managed to tie the game with Grossman finding Moss and Cooley on a 5-yard TD pass. The Cowboys managed to get the win after Buehler made a 39-yard field goal, settling both records at 5-9.

How many points behind were the Redskins after Buehler's first 20-yard field goal?
13