Eli Tomac of Cortez got off to a slow start in both motos Friday at Redbud National in Buchanan, Michigan, and finished sixth place overall.
Zach Osborne won both motocross races wire to wire and widened his series lead over Marvin Musquin, who finished fourth. Osborne now has 172 series points to Musquin’s 146.
Defending champion Tomac is 43 points behind Osborne in fourth place overall.
Tomac entered the Pro Motocross Championship event less than a week after winning the Ironman in Crawfordsville, Indiana.
Friday, he was fourth in Moto 1, after starting in ninth place. He made ground early in the race, moving into fifth place in Lap 6 and posting his fastest lap in Lap 8, at 2:05.88. But he was not fast enough to catch the leaders. Osborne went on to beat Musquin by 2 seconds, 17.444 seconds ahead of Tomac.
Chase Sexton finished third, followed by Tomac and Kawasaki teammate Adam Cianciarulo.
In the second moto, Tomac started in 11th place but moved up to seventh place in Lap 4 and fifth in Lap 10. Osborne again won wire to wire, beating Jason Anderson, Dean Wilson and Malcolm Stewart to the finish line.
Tomac was fifth, 8.8 seconds back.
Earlier Friday, Tomac qualified as the No. 3 rider after posting his fastest lap in 2 minutes, 3.804 seconds. Blake Baggett was fastest, at 2:03.759, and Cianciarulo was second at 2:03.765.
The Lucas Oil Pro Motocross Championship series will stay at Redbud National on Monday. The nine-race series then goes to Spring Creek in Millville, Minnesota, on Sept. 19; WW Ranch in Jacksonville, Florida, on Sept. 26; and Thunder Valley in Lakewood, Colorado, on Oct. 3. The series ends at Fox Raceway in Pala, California, on Oct. 10.