CHICAGO (AP) _ Autobot prevailed by a half-length after a stretch-long battle with Spellbound to win the 22nd running of the $160,600 Hawthorne Derby on Saturday at Hawthorne Race Course.

Autobot, ridden by Earlie Fires, went 1 3-16 miles over the turf course in 2:00 3-5 in besting 11 rival 3-year-olds.

Son Of The Desert finished third, 5 1/2 lengths behind Spellbound. Even- money favorite Double Feint, a challenger from New York, was fourth.

''He was trying, but he just wasn'g getting anywhere over the soft turf,'' jockey Robbie Davis said of Double Feint.

Spellbound set the pace while Autobot raced in fourth position down the backstretch. Moving up on the outside, Autobot came alongside Spellbound in the upper stretch, and the two fought it out the rest of the way.

''I had a good, clean trip,'' said Fires, who scored his third victory of the day. ''The little horse ran real hard.''

Autobot, owned and bred by the Happy Valley Farm of brothers Gary and Steve Wolfson of Jacksonville, Fla., earned $96,360 for his sixth victory in 15 starts.

The Kentucky-bred son of Command Central, who had previously won the Forerunner Stakes at Keeneland and the recent Oil Capitol Handicap at Hawthorne, has earned $208,066.

Autobot, carrying 120 pounds, compared with 123 pounds for the top-weighted Double Feint, returned $7.60, $4 and $4. Spellbound paid $8 and $6. Son Of The Desert paid $6.60.