The trials for the Grade 1, $899,523 Rainbow Derby for Quarter Horses will get off to a rousing start at Ruidoso Downs on Saturday, when champions American Runaway and Jls Mr Bigtime meet in the first of seven qualifying heats for the July 23 finale.The horses with the 10 fastest times will advance to the Rainbow, which has a record purse this year. There are 65 runners entered in the trials, which extend from the third through ninth races on a program that starts at 1 p.m. Mountain. Each of the races will be held at 440 yards. Other top horses running in the Rainbow trials Saturday include Flying Fig, last year’s champion 2-year-old filly, and Llano Teller, winner of last month’s Grade 1 Ruidoso Derby.American Runaway was voted the American Quarter Horse Association’s champion 2-year-old and champion 2-year-old colt for 2010, when he won the Grade 1 Ruidoso Futurity and finished second in his three other Grade 1 starts, the Rainbow Futurity, the Texas Classic at Lone Star Park, and the Remington Park Futurity.American Runaway has raced once since his championship season and finished a troubled fourth in trials for the Ruidoso Derby on May 28. In preparation for his second start since November, he has worked a bullet, going 330 yards from the gate in 17 seconds. The move was the fastest of 27 at the distance June 20 at Ruidoso. Paul Jones trains American Runaway for the partnership of Sammy and Johnny Martinez and Bobby Cox. G.R. Carter will ride from post 5.Jls Mr Bigtime will break from post 4. He will be seeking his fifth straight win Saturday. Jls Mr Bigtime was voted champion 2-year-old gelding for 2010, a season in which he finished second by a nose in the Grade 1 All American Futurity. He was the favorite for the Sept. 6 classic, and since that race has not lost. Jls Mr Bigtime has won two trials and two stakes back home in Louisiana, and even set a track record while winning a restricted Grade 1 at Evangeline Downs in December. Jacky Martin has the mount for trainer Darrel Soileau. Bodacious Dash and Hes too Icy for Me, who both edged American Runaway in separate Grade 1 races last year, meet in the fourth race. Flying Fig goes in the fifth, which will be her first start since December, when she was second by a nose in the Los Alamitos Two Million Futurity.