Donald and Adam Newman's Tani Maru gained command with about a half mile to go and galloped home to a convincing 9 3/4-length victory in Saturday's $97,000 Larry Riviello President's Cup at Philadelphia Park.It was the second victory of the year for the 3-year-old son of Cherokee Run, who was ridden by Harry Vega, and his second stakes win.Scratches reduced the field to just four runners and all four broke well. They headed into the first turn lined up across the track. Jockey Tony Black, stuck with the outside post aboard Letterman's Humor, wanted the lead but Vega had the inside post with Tani Maru and decided he would not let Black control the pace. The two battled for the first half-mile before Tani Maru took control.By the three-eighths pole, it was three-quarters of a length and, when they reached the quarter pole, a clear 1 1/2 lengths, and the race was soon over. The margin had reached almost ten by the time they hit the wire.Trained by Thomas Bush and off as a slight 7-5 betting favorite, Tani Maru returned $4.80 and $2.60 to win. Letterman's Humor returned $3.20. Russian Bay finished third.The final time for the one mile and seventy yards was 1:43.4.