Racing is a hobby for most drivers competing in the NASCAR Weekly Series at Las Vegas Motor Speedway.

Not so for Scott Gafforini and Justin Johnson, who will battle tonight at the speedway's Bullring for the season championship in the premier Super Late Models division, in which Johnson holds a two-point lead.

For those two, hobbies have become vocations.

Gafforini, 39, owns his race team as well as SG Speed Shop, which creates award-winning custom cars and street rods, and big-horsepower engines.

Johnson, 21, who graduated from Vo-Tech High School, works as a mechanic and high-performance driving instructor at the Spring Mountain Advanced Driving School in Pahrump.

"Anytime you work on a car and anytime you're driving (a racecar), you're getting experience and the practice you need to improve," said Johnson, who drives the No. 17 Dodge owned by Al Budd Racing and run by crew chief Brian Kizer.

Gafforini, a former automotive technician and sports car racer who drives the No. 38 Chevrolet, started racing on the three-eighths-mile oval at LVMS a year before Johnson began his career at the track.

The big difference was that Gafforini was 31 and Johnson was 13.

Another contrast between the two is that the young Johnson has won two track championships; Gafforini is seeking his first.

Johnson won the track's 2000 title in the Bandolero division, in which youngsters race miniature stock cars with motorcycle engines. He also captured the Legends Cars Pro championship four years ago.

It's not that Gafforini hasn't gotten close to winning the Super Late Models title. He's been runner-up in the series' top division five times since 1998. He was second to Mike Ray (1998), Chris Lowden (1999), Dick Cobb (2000), Thane Alderman (2002) and Chuck Trickle (2003).

In those seasons, the pressure of the chase was apparent as Gafforini tended to overdrive his car. This year, it has been quite different, as he seems more patient.

"I'd like to win it, of course, but if I do, it won't be the highlight of the past year. It'll rank third," said Gafforini, who married his wife, Amy, in December 2005. The couple had a daughter, Sonja, in April.

"Nothing can top becoming a dad," Gafforini said as his eyes watered and his voice cracked with emotion.

Johnson, who has seven victories this year to Gafforini's five, admits being anxious about tonight's 18th and final regular-season race.

"This week it's been the first thing I've thought about when I woke up and the last thing I thought about when I went to bed," Johnson said.

The Bullring gives points to the top three in qualifying, with the fastest getting three, second getting two and third receiving one. The race winner will get 50 points, with points declining by two for the top six finishers and dropping by one throughout the rest of the order.

Beyond the glory of being a track champion, both Johnson and Gafforini hope the title will help advance them to one of NASCAR's national series.

Gafforini said he is working to fund a five-race deal with sponsor Four Queens in next year's Craftsman Truck Series, including the Sept. 22 event in Las Vegas.

Johnson said he wants to continue with Budd's team next year at the Bullring unless an opportunity in a bigger series develops.

"Hopefully, this championship -- if I do win it -- will get me to the next level and open some eyes," Johnson said. "My heart's in NASCAR, and I want to make it to the (Nextel) Cup series."

• NOTES -- Track champs will be determined in five other divisions tonight, with racing beginning at 7:15.

If Chris Bray finishes 16th or better and qualifies first, he will win over Doug Hamm in Late Models; Brian Matzke, Phil Goodwin, Mario Opipari, Jim Petrie and Mike Heck are contending in Chargers; Aaron McMorran and Michael Morrissey vie in IMCA Modifieds; and in Legends Cars, Robby Guevara, Larry Toddy and B.J. Bollman can win the Masters title, and Josh Gross and Johnny Morrissey are contending for the Pro title.

Jeremiah Wagner (Legends Semi-Pro), Mitchell Taylor (Bandolero Young Guns), Blake Leuth (Bandolero Bandits), Bobby Ruppert (Thunder Roadsters) and Matt Larsen (Bombers) already have clinched titles. ...

Speedway officials early this week suspended Super Late Models driver Billy Mitchell until June 1 for a rough driving incident with Tony Clark Sept. 30 at the Bullring. Clark is on probation through the end of 2007.