Red Bull KTM’s defending Monster Energy AMA Supercross champion Ryan Dungey has clinched a fourth-career 450SX title after a thrilling final round in Las Vegas.

Fourth was enough for Dungey to capture the crown by five points over Eli Tomac (Monster Energy Kawasaki), who was second in the main event won by Jason Anderson (Rockstar Energy Husqvarna).

Anderson took his first main event victory of the season ahead of Tomac and Josh Grant (Monster Energy Kawasaki), but it was Dungey in P4 who won the war on-board his 450 SX-F. Australia’s Chad Reed rode his Yamaha to sixth.

The final got underway with RMATV/MC-WPS-KTM’s Blake Baggett edging out Dungey for the SupercrossLive.com Holeshot. Dungey used the momentum of an outside line to quickly move into the lead, while Tomac fought his way into third behind Baggett. With his championship rival out front, Tomac wasted little time in working his way around Baggett for second.

Tomac’s push continued into lap one when he made an aggressive pass on Dungey, who took counter action to avoid contact and ended up losing another spot to Anderson, dropping to third. It was then Anderson’s turn to apply pressure on the lead.

He stalked Tomac for several laps, and even briefly nosed his Husqvarna to the front, but his aggressiveness allowed Dungey to close back in and take over second on lap four. The race stabilised a bit at that point, with Tomac enjoying a multiple-second lead, but as the 20-minute-plus-one-lap Main Event neared the halfway point Dungey began to close back in on his rival.

A miscue in a rhythm section on lap 14 allowed Dungey to surge past Tomac and back into the lead, but the Kawasaki rider stayed right on his rear fender. A short time later Tomac dove to the inside of Dungey, forcing contact and sending the KTM rider off the track.

As Tomac reclaimed the lead, Dungey was forced to safely reenter the track and did so without losing a spot, but came out just in front of Anderson. At this point in the race, the top six riders sat within three seconds of another, adding to the tension both on the track and in the stands.

Reed made his presence felt on lap 17, working his way into the lead group and passing Anderson for third. However, in the final turn before the finish Anderson attempted to retake the position, forcing heavy contact with Reed and sending the Monster Energy/Yamalube/Chaparral/Yamaha Financial Services/Yamaha Factory Racing rider off-track.

Reed would re-enter the race in sixth. The incident also allowed Monster Energy Kawasaki’s Josh Grant to briefly take over third from Anderson, but the Husqvarna rider fought back and reclaimed the position.

As the field took the white flag for the final lap the capacity crowd rose to its feet as Dungey continued to manage about a bike-length deficit to Tomac, seemingly waiting for a final opportunity to make a move and potentially steal the win. As the leaders approached the track’s lone triple jump for the final time Tomac went high and suddenly dropped off the pace, which allowed Dungey to easily move back into the lead.

Tomac’s brief slowing appeared to be intentional as he jumped right behind Dungey and came in with another aggressive pass in the next corner. The two made contact again, forcing both to stop completely and nearly go off the track. That allowed Anderson to dive under the lead pair and jump from third to first with just a few turns remaining.

Grant briefly followed into second, but Tomac regained his momentum and got back by. Dungey received the worst of the situation, falling from second to fourth, but he kept his KTM on two wheels and settled for the spot he needed in order to ensure the title.

Anderson went on to take an unexpected win, the third of his career and his first of the 2017 season, by 1.8 seconds. Tomac followed in the runner-up spot after leading 17 laps, with Grant claiming his first podium finish of the season behind his teammate in third. Needing a finish no worse than fourth, Dungey brought his KTM home just off the podium.

Dungey shared his frustration with the Kawasaki teammates for their race tactics after crossing the finish, but a fourth Monster Energy Supercross Championship was his.

In the 250SX main event it was Adam Cianciarulo (Monster Energy/Pro Circuit/Kawasaki) who won ahead of West Coast champion and teammate Justin Hill, as Aaron Plessinger (Yamalube Star Racing Yamaha) filled the podium.

The 250SX Class East/West Showdown kicked off with Cianciarulo storming to the SupercrossLive.com Holeshot, just ahead of his teammate Joey Savatgy and Troy Lee Designs/Red Bull/KTM’s Jordon Smith, the Eastern Regional points leader.

This trio, along with Osborne, entered the night mathematically eligible to win the title and while three of the four sprinted out to an early lead, Osborne found himself picking up his Husqvarna off the ground following a first-turn crash that collected several riders. Osborne began his race at the tail end of the field, completing the first lap in 21st.

The clear track allowed Cianciarulo to sprint away, but Savatgy kept pace. As they crossed the line to officially start the first lap, Savatgy washed out his front end in the first corner and went down. That allowed Smith to take over second, with Rockstar Energy Husqvarna Factory Racing’s Martin Davalos moving into third.

The lap one excitement sparked again when Smith went off the side of the track while running second. He kept his KTM on two wheels, but lost several positions and reentered the race in fifth. That moved Davalos into second and Monster Energy/Pro Circuit/Kawasaki’s Justin Hill, the newly crowned Western Regional champion, into third.

Davalos would encounter misfortune on lap two and fall out of contention, moving Hill into second and 51Fifty Energy Drink Yamaha’s Hayden Mellross into third. Smith endured even more misfortune of his own on the same lap, suffering a frightening crash that would bring his race to an end and eliminate his hopes of a first career title.

With Cianciarulo in full control of the race out front, Savatgy running in fourth, and Osborne slowly working his way back into the mix in 20th, the championship intrigue was only beginning. Over the middle portion of the 15-minute-plus-one-lap main event both Savatgy and Osborne began heading in opposite directions.

Savatgy, who controlled his own destiny in the title fight, continued to lose ground to the riders behind him, falling from fourth to seventh on lap five. Meanwhile, Osborne was charging through the field and broke into the top 15. Savatgy would lose another position and fall to eighth three laps later.

With the final winding down, Savatgy’s vulnerable hold of the championship lead left him with just a single-point advantage over Cianciarulo as they ran on track, while Osborne’s continued improvement also allowed him to close to within single digits of the points lead.

On lap 12 Osborne valiantly fought his way into ninth, with only Savatgy sitting between he and his first career title. A large gap sat between the two as the time on the Main Event clock expired, but with one additional lap remaining the Husqvarna rider was able to make a charge to Savatgy’s rear fender and within striking distance on the final lap.

Cianciarulo dominated the race and posted a wire-to-wire effort to capture his second victory of the season, likely unaware of the bedlam ensuing behind him. He crossed the line 5.7 seconds ahead of Hill, while Yamalube/Star Racing Yamaha’s Aaron Plessinger made an impressive climb from a 15th-place start to round out the podium in third.

As they approached the final set of whoops on last time, Osborne committed to making a pass attempt on Savatgy for seventh and did just that, diving to the inside of an unsuspecting Savatgy and drawing heavy contact that ripped Savatgy off the back of his Kawasaki after it briefly hooked onto Osborne’s Husqvarna. Osborne continued, leaving Savatgy to pick up his bike, and ultimately clinched a title that didn’t seem possible after the opening lap.

Osborne’s seventh-place finish, coupled with Cianciarulo’s win, left them just two points apart in the final standings. Cianciarulo entered the night 14 points out of the lead, while Osborne and Savatgy sat just a single point behind Smith. Savatgy ended up 12th and wound up seven points back.

Of the Aussies, Mellross eventually crossed the finish-line eighth, while Dan Reardon (Yamalube Star Racing Yamaha) brought his YZ250F home in position 13.