Denny Hamlin snatched the lead in a final pit stop under yellow and won at Darlington Raceway in overtime for his second consecutive Cup victory.
William Byron, who dominated the race, finished second, followed by Christopher Bell, Tyler Reddick and Blaney, who was leading with three laps remaining in the scheduled distance when the final caution flew for a spin by Kyle Larson.
Hamlin emerged from the pits with the lead for the final two-lap shootout ahead of Reddick and Byron. Blaney fell from first to fourth on the last pit stop.
Hamlin, who won last week at Martinsville Speedway to end a 31-race winless drought, won by 0.597 seconds in his No. 11 Toyota. With his 56th career victory, he broke a tie with Rusty Wallace for 11th on the all-time win list in NASCAR's premier series.
Reddick pitted on Lap 240 of 297 and took the lead eight laps later in his No. 45 Toyota.
Byron led the first 243 laps on the 1.366-mile oval before his strategy went awry on the final pit stop. Byron pitted on Lap 244 of 293, two laps behind Bell and four laps behind Reddick. After blending onto the track behind Reddick and Bell, Byron fell several seconds off the lead in third place.
Blaney chased down Reddick to take the lead on Lap 290 and seemed headed for his first win of the season before the caution flew for Larson.
Byron swept both stages by leading the first 185 laps. He became only the second driver since the advent of stage racing in 2017 to lead every lap of the first two stages.
Byron also became the first driver to win a stage at Darlington while leading wire to wire.
WILL BE UPDATED
Stage 1 winner: Byron
Stage 2 winner: Byron
Next: Sunday, April 13, 3 p.m. ET at Bristol Motor Speedway on FS1
