J.D. Acosta is better known as the leading rider at Charles Town, but for the past two seasons, the 27-year-old jockey has also been the king of Maryland's last remaining bullring.\nFor the next couple of weekends, Acosta will be doing double duty, riding in the afternoons at Timonium and at night at Charles Town.\nTimonium, which held its first meet in September 1887 and is the only state fair east of Texas still to offer Thoroughbred racing, opens its seven-day meet in conjunction with the Maryland State Fair on Friday.\nLive racing on the five-eighth-mile oval will also be held this Saturday and Sunday, and again from Sept. 4 through Labor Day. Post time is 1 p.m. Eastern.\nAcosta, who won 14 races at Timonium in 2007 and 10 more a year ago, including five on the closing-day card, is named on nine horses on Friday's program, a total that includes two mounts apiece in races 4, 6, 7, and 8.\nThree of the horses Acosta is named on are for trainer Chris Grove. As a team, Acosta and Grove went 3 for 4 at last year's Timonium meet.\nGrove has given the call to Acosta on Disco's Wish in race 6, first-time starter Bishop's Head in race 7, and Deac, a maiden who has been off since March 2007, in race 9.\nIn Friday's nominal feature, a first-level allowance for fillies and mares going four furlongs, Acosta must choose between Next Big Nothin', a 3-year-old who has won back-to-back starts racing 4 1/2 furlongs at Charles Town for high-percentage trainer Dale Capuano, and Swift Concorde, a filly he has been riding for Tim Salzman. She most recently won her maiden sprinting 4 1/2 furlongs at Charles Town.\nJohn Robb, last year's leading trainer with 5 wins in 12 starts, comes into this year's meet on a roll after winning with 7 of 9 starters at Laurel Park's recently concluded mini-meet.\nRobb has a pair of first-time starters entered Friday, a 2-year-old named Mr. Raven in race 3 and 3-year-old colt Bodiddle in race 4.\nFriday's card attracted 79 runners for nine races.