The Supercross will be the last of three motorsports events at the Padres' downtown home. Petco Park also hosted two Monster Truck shows, Jan. 17 and last Saturday.
Saturday's 31st San Diego Supercross will be the first at Petco Park, and it will feature a tighter and more technical layout than local fans previously saw at Qualcomm Stadium.
The 13-event national Supercross tour is the world's most popular motorcycle series.
Dungey, 25, won the Supercross season championship in 2010, and he rode his KTM to victory last Saturday in Anaheim to open an 11-point lead on Roczen.
Roczen, who is riding for the Suzuki team co-owned by former champion Ricky Carmichael, has won two of the season's first five events.
Honda riders Eli Tomac (a two-time San Diego winner in the 250cc support class) and Trey Canard are tied for third in the standings, 12 points behind Roczen. Tomac and Canard each have a win this season.
The 2015 season is one of the most competitive in recent seasons, as the tour is without two of its top riders.
Four-time series champion Ryan Villopoto, 26, announced his retirement from Supercross on the opening night of the 2015 season, and he plans to ride in Europe this year. Defending San Diego race winner James Stewart will miss this season while serving a suspension for using a banned substance.
Dungey scored his 13th event win at Anaheim. He will be looking for his first win in San Diego, which has produced five winners over the past five years. The only past San Diego winners in this year's field are Davi Millsaps and 32-year-old former series champion Chad Reed of Australia.
Millsaps won twice at Qualcomm Stadium, in 2010 and '13. Reed won a record six San Diego Supercrosses, most recently in 2011.
In addition to the featured 450cc motorcycles, the event also features the 250cc support class, where Cooper Webb has won four of the season's first five races.
Saturday night's program officially starts shortly after 7 p.m. PT, with eight races in the two classes over the obstacle course. But the gates open early for practice and qualifying, with tours of the pits adjacent to Petco Park also available. Parking will be at a premium, and fans are encouraged to arrive early and use public transportation.