The NASCAR Cup Series race will resume on Monday at 11 a.m. MT (1 p.m. ET) and will be televised on FOX.
Ryan Blaney got off to a strong start but his race ended in a crash on lap 117 when he failed to avoid a collision between Trevor Bayne and Chris Buescher, so Kyle Larson will be the leader when the action resumes. A mad shuffle on that race restart saw the fifth-year Cup driver pull away from veterans Denny Hamlin, Paul Menard, Kyle Bush, Ricky Stenhouse and Joey Logano - the running order at the time the race was postponed.
Ryan Blaney appeared to have the auto to beat in the early going.
Busch was fourth-fastest in Happy Hour, but on his 70th lap of the session, his No. 41 Stewart-Haas Racing Ford lost traction in Turn 2, spun sideways, slid down the backstretch and nosed into the inside SAFER barrier near the entrance to Turn 3.
The race started about 30 minutes later than planned amid a forecast that includes a 100 percent chance of rain. Martin Truex Jr., who qualified 26th, was second fastest in Saturday's first practice at 128.952 miles per hour. Chastain's is the only auto that had to go behind the wall.
Keselowski hustled to his vehicle and got in to drive a few laps. "I think he looked at that [six]-race stretch and his average finish was like the second- or third-best in the Cup Series during that". He had led 74 laps on the half mile track before the rain caused the third and final stoppage.
However, it remains unclear if the rain will hold off long enough to get the race in.
There will be a competition caution after 45 laps to reassess the track. The team has gone to a backup auto, which means Busch will need to start at the rear of the 39-car field.
BC-CAR-NASCAR-Bristol, 1st Ld-Writethru, 149NASCAR hopes to run Cup race at Bristol despite wet forecastAP Photo TNWP103, TNWP102, TNWP101, TNWP104Eds: APNewsNow.
Some drivers won't have to worry about coming back April 16. NASCAR is attempting to dry the track after heavy morning rain subsided. But Monday's forecast isn't a whole lot better. Last spring's Bristol race was also contested on a Monday.