The first caution of the Auto Club 400 has just ended, following a Fontana-record 75 laps under green to start the race.
Kyle Busch's Toyota has been out front for most of the event since he overhauled teammate Denny Hamlin to grab the top spot. Hamlin had slipped back as Martin Truex Jr. and Tony Stewart both moved around him.
Jeff Burton, who ran in the top-ten, was caught speeding on his second green-flag pit stop and forced to make a pass through penalty. Busch had caught him to put him a lap down when the caution flag waved.
Defending race and series champion Jimmie Johnson has been a non-factor to this point, getting as high as tenth place during the first run of the race but langushing outside the top-ten otherwise.
Stewart did not stop under the caution flag, so he has assumed the lead for the second time today, after holding it briefly during the last cycle of green-flag pit stops.