Sadler, who led the way in practice earlier in the day, posted a lap at 186.348 mph around the fast 1.5-mile track for his fifth pole of the season and the 11th of his Nationwide career. He won the pole at Texas for the first time in 1998.
Busch qualified just 0.004 seconds behind Sadler. He has won the most Nationwide races at Texas with six.
Danica Patrick will start 11th. Earlier in the day, Patrick announced her partial Sprint Cup Series schedule for Stewart-Haas Racing in 2012. She will make her debut in NASCAR's premier series in the February 26 Daytona 500.
Kenny Wallace qualified 18th in what will be his series-record 520th start.
With three races to go, Stenhouse holds a 15-point advantage over Sadler.
Erik Darnell, Mark Green, Matt Carter, Johnny Chapman and Dennis Setzer failed to qualify for Saturday's 300-mile race at Texas, which is scheduled to start at 12:55 p.m. (et).