Corey Day continued his impressive rookie season Saturday by earning his second career NASCAR O’Reilly Auto Parts Series victory in dramatic fashion at Dover Motor Speedway.

The 20-year-old Californian tracked down series points leader Justin Allgaier in the closing laps of the BetRivers 200 and made the winning move with just four laps remaining. Using the high groove against Dover’s outside wall, Day split around a lapped car alongside Allgaier and powered away to secure the win by 0.461 seconds in his No. 17 Hendrick Motorsports Chevrolet.

The victory came just three weeks after Day earned his first career series win at Talladega Superspeedway, but this one carried a different feeling for the young driver.

“Man, I was hoping that’s how it would play out,” Day said after climbing from his car. “I saved so hard there early in the last run once we put on tires and the yellow came out and I thought, aw, this is just going to be a caution fest and it was all for nothing, but oh man, it all just worked out good.

“This one feels really, really good,” Day added. “The Talladega one was unexpected at a superspeedway, but we earned this one.”

Day’s mentor, reigning NASCAR Cup Series champion Kyle Larson, watched the closing laps from atop the pit box and celebrated with the Hendrick Motorsports team after the checkered flag.

Allgaier appeared headed toward his fourth victory of the season after leading a race-high 71 laps, but traffic changed everything late in the race. As Allgaier approached lapped traffic, Blake Lothian’s car moved between lanes, creating just enough hesitation for Day to pounce to the outside and take the lead for good.

“Good teaching moment,” Allgaier said after speaking with Lothian on pit road. “He kind of made a move to inside then back outside and I just didn’t know which lane he was going to go in. And unfortunately, it allowed the 17 to get to my outside.

“But hats off to Corey and that whole 17 team. He was running me down there at the end.”

Despite the disappointment, Allgaier still extended his championship lead to 175 points over Sheldon Creed after another strong performance.

Sam Mayer brought home a third-place finish for Haas Factory Team, while Joe Gibbs Racing rookie William Sawalich finished fourth. Austin Hill rounded out the top five with his best finish since March’s race at Circuit of the Americas.

The race featured nine cautions and several strategy shifts throughout the afternoon.

Brandon Jones captured the Stage 1 victory, while NASCAR Cup Series regular Ross Chastain won Stage 2 after leading 68 laps. Chastain looked like a contender for the win until contact with Taylor Gray shortly after the halfway point sent both drivers spinning and ended his chances.

JR Motorsports driver Carson Kvapil finished sixth and extended the organization’s remarkable top-10 streak to 71 consecutive races. Ryan Sieg, Sammy Smith, and Anthony Alfredo completed the top 10.

The NASCAR O’Reilly Auto Parts Series now heads to Charlotte Motor Speedway for next Saturday’s Charbroil 300, where NASCAR Cup Series star William Byron enters as the defending race winner.