ARLINGTON HEIGHTS, Ill. - Steve Asmussen had been spotting Sky Mom in races up to about a mile, thinking that the 3-year-old filly would start losing her effectiveness at longer distances. But Sky Mom's closing second-place finish to Storm Mesa in the 1 1/16-mile Iowa Oaks last month started Asmussen thinking differently, and his plan to let Sky Mom run longer bore fruit Saturday at Arlington Park, where Sky Mom won the 1 1/8-mile Arlington Oaks over hard-trying pacesetter Dreaming of Liz.