Legendary Moto-X 338 will provide the most unique challenge of the 2012 season as the lone stop of the Nationals to feature sand, which provides an ever-changing surface sure to keep the world’s best riders at their best. This weekend marks the series’ 34th visit to Southwick, which has been the site of some of the sport’s most memorable moments.At the championship’s previous stop from Washougal MX Park, Red Bull KTM’s Ryan Dungey overcame a stiff challenge from MotoConcepts Suzuki’s Mike Alessi to take his sixth straight overall victory and maintain his dominant hold on the 450 Class point standings. While Dungey’s streaking ways continued for the overall win, his string of moto victories was halted at 10 after a captivating battle with Alessi in the opening moto.Assuming the role of Dungey’s primary challenger for most of the season, Alessi’s breakthrough moto win served as the first for his MotoConcepts team while also ending a winless streak for the Suzuki rider that dated back to the 2010 season. With the anticipated return of Team Yoshimura Suzuki’s James Stewart at Southwick, Dungey’s competition will arguably be stiffer than what he’s seen since taking over the points lead at the third round.Last season at Moto-X 338, Team Yoshimura Suzuki’s Brett Metcalfe overcame heavy rains from incoming Hurricane Irene to claim his first career motocross victory. Behind him, both Dungey and eventual champion Ryan Villopoto were forced to overcome their own bouts of misfortune, ultimately tightening the championship. With both Metcalfe and Villopoto out due to injury, Dungey will look to secure his second 450 Class win at Southwick.A mere 11 points separates the top two riders in the 250 Class, with Monster Energy/Pro Circuit/Kawasaki’s Blake Baggett leading the way over GEICO Honda’s Justin Barcia. At Washougal, Barcia withstood strong performances by both Baggett and his teammate Eli Tomac to become the third rider this season to amass multiple victories.This trio of riders have led the way in the division throughout the 2012 season, trading victories between one another at each round. With four races and eight motos remaining, the 250 Class title fight is far from over heading to a venue that Barcia considers to be one of his best tracks, having won at Moto-X 338 during the 2009 season when he was a rookie.Last year at Southwick, Tyla Rattray secured his second consecutive win in the sand with a strong 2-1 outing.The Women’s Motocross Championship will host its penultimate round of the 2012 season at Southwick, with a captivating battle for the title taking shape. Currently, Rockstar Energy Racing Suzuki’s Jessica Patterson holds a slim two-point lead over Troy Lee Designs/Lucas Oil Honda’s Tarah Gieger, while defending champion Ashley Fiolek is making a hard charge in third aboard her Team Honda Muscle Milk machine, 11 points out of the top spot.Despite suffering a broken hand prior to the RedBud round, Patterson has continued to fight through the pain on the track. However, in the two rounds since she suffered the injury, her championship advantage has reduced significantly from 33 points. While Fiolek has claimed back-to-back wins to claw her way into the championship picture, Gieger has put forth consistent rides to put herself in position to claim a first career title.Last season at Moto-X 338, Fiolek secured the victory over Gieger, while Patterson experienced misfortune. With this familiar threesome of the fastest women on the planet all within striking distance of the coveted championship, Southwick is sure to play a pivotal role in the outcome of the season.Moto-X 338, named after American Legion Post 338, which owns the property, has been hosting motocross events since the 1973 season. Just three years after the facility opened, the Lucas Oil Pro Motocross Championship held its first event in Southwestern Massachusetts, Since then, Moto-X 338 has been a staple on the schedule and one of the most anticipated stops of the season. Affectionately referred to as the “sand box” and “the beach,” Southwick is a fan and rider favorite, year-in and year-out.This year, Moto-X 338 and The Jimmy Fund are teaming up to give away 2012 Kawasaki KX450, along with other great products from Chaplin Kawasaki, New England Race Fuel, and Factory Connection. A $5 donation will provide an entry into a drawing that will take place on Saturday during the motos to determine a winner. Follow the Lucas Oil Pro Motocross Championship social media outlets for more details or go to motocross338.org/jimmy-fund/.The Moto-X 338 National will feature live broadcast coverage of the first 450 and 250 Class motos on FUEL TV and AlliSports.com, beginning at 1 p.m. Eastern. Tape-delayed coverage of the final motos of each class can be seen on NBC Sports Network on Tuesday, August 14 at 4 p.m. Eastern.