Kyle Busch, racing in the second of three NASCAR races in a historic weekend triple, finished 20th, three laps down. A green flag pit stop with 52 laps to go bounced him from the top five to two laps down.
Keselowski, driving for Dale Earnhardt Jr., became the seventh first-time winner in 15 Nationwide races at Nashville Superspeedway. David Stremme rallied to finish second, followed by David Reutimann and Bowyer.
"I heard Dale's satellite went out with 10 laps to go so he must be crying," said Keselowski.
Busch's setback came 24 hours after his second-place finish in the Craftsman Truck Series race at Texas Motor Speedway.
By starting Sunday at Pocono, the Sprint Cup Series leader will become the first driver to compete in all of NASCAR's top three series at different tracks on the same weekend. Busch will start in a backup car at the tail of the field, the result of a crash earlier Saturday that destroyed his primary car during practice.
Just as he did at Pocono, Busch bolted from his hauler and left the speedway without talking to reporters.
"He said the car drove really good and we were easily among the top five cars," said Trent Owens, Busch's crew chief. "After the first pit stop we had a car that could contend for the win.
"Performance-wise, Kyle was very happy with coming in and qualifying fifth without practicing the car and running amongst the top five."
Busch ran into problems when he got into a scrape with pole-sitter Joey Logano on lap 88. Making only his second career start, Logano led 64 laps before touching off the altercation when he got out of shape in four-wide traffic.
Busch cycled back into the top five late in the race before the green flag stop.
"The fender gave way just from being weak," Owens said. "We beat it back out but it got back on the tire and rubbed a hole in the side wall. It's unfortunate luck. (Logano) ran into the side of us, messed up the front end alignment and the aerodynamics. We lost some speed and just never got it back."
Logano, who drives for Joe Gibbs Racing, has tested Cup cars at Nashville Superspeedway but this was his first time over the track in a Nationwide car. Logano qualified with a lap of 159.944 mph over the 1.3-mile concrete oval and had led a race-high 64 laps at the time of the accident.
"It's definitely cool to get my first pole in the second try," Logano said. "But it's what I expect of myself. I expect to win. This thing here doesn't excite me too much. It's just a pole."
Keselowski started second and was never lower than seventh in the running order.
"When the race started we were a little tighter than we wanted to be," said Keselowski's crew chief, Tony Eury Sr. "We worked on it every stop, made some adjustments and it worked out."
A caution with 12 laps to run played into Keselowski's hands.
"We just caught up to Clint there when yellow came out (for Brad Teauge) and it's what we needed to catch back up. We were gaining but we wouldn't have had a chance without the caution," Keselowski said.
"We had a strong car, there's now doubt about that. It came down to strategy. We pitted with about 40 laps to go. We were digging and passing one at a time. It seemed like we were taking forever.
When racing resumed, it only took Keselowski three laps to take the lead.
"That's what it takes to win these races," Keselowski said. "The shoe's been on the other foot before."
A year ago, Keselowski left Nashville unemployed as his previous team folded. He was picked up by Earnhardt shortly thereafter.
"It was about as bad as you could get," Keselowski said. "We came here with a road course car. We broke down about five times and it made me question why I was doing this.
"They folded up right after that and I was out of a job until I got with Dale."
Keselowski became the first Nationwide driver this season to take his first victory in the series.
Bowyer held on to the points lead but Reutimann passed Busch to move into second, 166 points behind the leader. It's another 22 points back to Busch in third. In addition to Busch, Bowyer and Reutimann, three other Sprint Cup regulars were in the lineup. David Ragan finished fifth, Greg Biffle was 10th and Carl Edwards finished 13th.
