(CNN) -- "We did it!"
That exultant Tweet came from Brad Keselowski as he rolled into pit row after Sunday's season-ending race, the Ford EcoBoost 400, at Homestead-Miami Speedway in South Florida.
Keselowski didn't come in first, a prize that went to Jeff Gordon. But his 15th-place finish was more than enough for the 28-year-old to cinch his first ever Sprint Cup championship as NASCAR's top driver this year.
"It means the world -- it really does," Keselowski said, according to a story on NASCAR.com. "I've got the best team in racing, and I'm just so thrilled to be a part of it."
The honor capped a breakthrough year for the Michigan resident, who began racing full time in 2010 on the senior racing circuit. He posted five wins (more than doubling his career total), as well as 13 top-5 and 23 top-10 finishes.
Considering those statistics, Sunday's race might have been considered a letdown for Keselowski. But it didn't matter, considering his next closest foe -- and the only other driver, coming into the race, with any chance to claim the title -- Jimmie Johnson didn't even finish.
The five-time series championship winner bowed out after the 224th lap due to mechanical problems, clearing the way for Keselowski.
Gordon had reason to celebrate as well, by beating Clint Bowyer by just over a second to win the race.
Just last week, Gordon ran into Bowyer at a race in Phoenix, Arizona -- causing a wreck that basically removed any last hopes Bowyer had for a championship. Afterward, Gordon took part in a brawl with members of Bowyer's pit crew, which prompted NASCAR to fine him $100,000.
Keselowski also had to pay a fine after that race, though it had nothing to do with fighting. Rather, NASCAR docked him $25,000 for breaking its rules by having a cell phone in his car.
No word on whether more fines might be coming, given that Keselowski shot a picture from inside his car Sunday night, which he then shared with the world via Twitter. But any penalty seems unlikely to significantly damper the new champion's enthusiasm.