The #11 Joe Gibbs Racing Toyota Camry driver looked like he had sewn up the series until William Byron crashed his #24 Hendrick Motorsports Chevrolet Camaro with three laps to go.
Some cars stayed out, most cars pitted, and the decision to take four tyres instead of two ultimately proved the difference.
Kyle Larson, driving the #5 Hendrick Camaro, got track position, restarted fifth, and romped home to finish third while Hamlin could only muster sixth.
It was a cruel end to the contest at Phoenix. Hamlin came into stock car racing’s winner-takes-all grand final with a lot on his mind.
An enormous legal battle with NASCAR was merely an afterthought for Hamlin, whose father lay bedridden by illness.
This, according to Hamlin, was his last chance to win the title while his father still lived.
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“I really don’t have much for emotion right now,” said Hamlin.
“Just numb about it ’cause just in shock. That’s about it.
“In this moment, I never want to race a car ever again,” he said with a wry smile.
“I mean, my fun meter is pegged.”
Hamlin led 208 laps of the 319-lap race distance.
All four championship contenders had tyre issues in the race.
When Shane van Gisbergen spun the #88 Chevrolet Camaro on Lap 46 and brought out the yellow, Hamlin’s left rear tyre went down.
Then Chase Briscoe in the #19 Joe Gibbs Racing Camry had a tyre go down on Lap 104, an issue that reared its ugly head again later in the race on Lap 215.
Larson lost a lap with a puncture on Lap 215 moments before Briscoe, and then Byron crashed the #24 Hendrick Camaro out of contention with three laps to go.
He suffered a slow pit stop as a result, and fought his way back to the front after dropping outside the top 10.
“They did a great job,” Hamlin said of his team.
“We had one hiccup, but it wasn’t their fault. We got fortunate with the left rear tyre that was flat under caution. They executed a great day.
“Man, I really wish I could have got it for them.
“[It] wouldn’t have changed anything I felt truly about myself. I wanted it so bad for everyone else, all of my supporters, all my friends and family and whatnot, that they want it so bad.
“Just not going to happen. Did the best I could. Everything I really prepared for happened today. I felt like we responded. Even losing track position at one point, just battling back.
“The team brought a great championship car. I felt like I drove it just right up until two laps to go.
“Yeah, this is the part that stinks.”
Hamlin couldn’t quite believe his luck when Byron crashed.
“Well, I mean, we’re 40 seconds from a championship,” he said.
“I don’t know. It’s just unfortunate.
“The only difference before is the cautions came maybe a little sooner than that.
“Gosh, you work so hard.
“This sport can drive you absolutely crazy, ’cause sometimes speed, talent, all that stuff, just does not matter.”
Even though Hamlin was two rows behind Larson for the final restart, he thought the benefit of four tyres over two would pay dividends.
“I didn’t think it was over. I thought, well, all right, let me see where the other guys are at,” Hamlin explained.
“Surely they can’t jump too far in front of me. I just didn’t think there would be that many cars that took two tyres.
“It’s really hard to predict how many cars are going to do what, things like that. But I didn’t think it was over.
“When I lined up [on] row five, I thought, it will be difficult, for sure.”
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