Jockey Winston Thompson won six races on Saturday's 11-event program at Suffolk Downs, including the featured $50,000 Old Ironsides Breeders' Cup Stakes on the turf course aboard Live Oak Plantation's Miesque's Approval.It is the first six-win day of Thompson's career, which includes four five-win days at the East Boston oval. He becomes just the seventh rider in track history to record six victories on a single card, last accomplished by Rudy Baez in both 1993 and 1997. Leroy Moyers holds the track record with seven wins on July 4, 1967."It took plenty of luck for this to happen," said Thompson, who is currently atop the Suffolk rider standings with 41 wins. "Things fell into place for me and that doesn't always happen. I have to give much of the credit to my agent, Max Hall, and especially trainer Kevin Clark." Thompson rode three winners for Clark on Saturday. "He has won 16 races this meet, and I have ridden every one of his winners," the jockey noted.Miesque's Approval cruised patiently in third down the backstretch before making his move on the far turn, taking the lead at the top of the stretch and galloping to a 2 3/4- length victory as the odds-on choice in a field reduced to eight after four scratches."The scratches helped me because I had the outside post, and it allowed me to save more ground into the first turn," said Thompson. "He wanted to take the lead moving down the backstretch, but I just kept him clear like you should do with a horse that is much the best. I heard the others coming late, but had plenty of horse still under me." The 6-year-old son of Miesque's Son, trained by Bill Mott, covered the mile and 70 yards on the grass in 1:43 4/5, paying $4.00, 2.60, and 2.40. Longshot Canyon's Way was second, returning 12.00 and 5.00. Tom the River Rat paid 4.20 to show.Thompson's other wins were aboard Marlin Bay (race 2, $4.40), Pegasus Cyberspace (race 4, $8.20), Assets of Gold (race 5, $7.80), Imablazinbeauty (race 6, $7.00) and Knock Out Prospect (race 10, $4.40).