William Byron spins and suffers mechanical failure in Chase opener at Darlington

Here's the thing about the opening race of the NASCAR Cup Series Chase presented by Mobil 1 at : it can chew you up and spit you out in a heartbeat. Unfortunately, that is exactly what happened to . The No. 13 seed saw a promising run come to a sudden and brutal halt late in the Cook Out Southern 500.

Running in ninth place at Lap 316, Byron suffered a spin that sent him sliding down to the apron of Turn 3. From there, his machine skidded back across Turn 4 before finally coming to a stop right at pit entry. It was a wild moment, but he managed to get his No. 24 Hendrick Chevrolet re-fired.

That relief lasted only a brief moment. Speaking to USA Network, Byron explained that he initially felt something dragging and believed a tire was going down. But as the field filed for the restart, the No. 24 car started billowing thick smoke, forcing him straight to the garage and ending his afternoon for good.

When he talked to reporters after the race was officially over, the exact cause of the engine trouble remained a mystery. “Still trying to figure it out,” Byron said of his mechanical issue. “But yeah, super odd, I don’t know. I had some sort of issue and then eventually something broke. Whatever, I’m not sure.”

That sudden failure left him saddled with a 37th-place finish, collecting a meager six points on the day, with five of those coming purely from stage points. It is a harsh blow when you consider he spent much of the second half of the race fighting inside the top 10.

Before this disaster, Byron came into the event sitting 85 points behind top-seeded for the series points lead as the postseason kicked off. Now? He has plummeted all the way to 16th place—last in the Chase standings—with nine races remaining, leaving him 114 points back from Hamlin.

Despite the heartbreak, there was at least some pace in the machine before everything went wrong. “I thought we did a good job to have good speed,” Byron said, “but just gotta continue working. So we’ll do that.”