Four graded stakes winners, led by recent Brooklyn Handicap hero Birdrun, will challenge defending champion A.U. Miner in Saturday&rsquo;s $200,000 Greenwood Cup at Parx Racing.\r\nThe 10 older horses in the 1 1/2-mile Greenwood Cup will be looking to secure an automatic berth in this fall&rsquo;s Breeders&rsquo; Cup Marathon at Churchill Downs. The Greenwood Cup, along with Turf Monster later this season, are the two Parx races on the calendar that are part of the Breeders&rsquo; Cup&rsquo;s Win and You&rsquo;re In program.\r\nAlthough A.U. Miner got up by a neck to win last year&rsquo;s Greenwood Cup at 14-1 and finished a respectable fourth, despite getting bumped and having to steady with five-sixteenths of a mile remaining in the Breeders&rsquo; Cup Marathon, the 5-year-old Birdrun is the logical favorite in Saturday&rsquo;s race.\r\nBased in New York with trainer Bill Mott, Birdrun is coming off a wire-to-wire, 1 3/4-length score in the Grade 2 Brooklyn going 1 1/2 miles at Belmont Park on June 10. He prepped for that race by finishing second, beaten a mere neck, by Belmont Stakes winner Drosselmeyer in an overnight stakes contested at 1 1/4 miles.\r\nThe other Greenwood Cup entrants with a Grade 3 win on their r &eacute; sum &eacute; are Afleet Again, Ron the Greek, and Chirac. In each case, Grade 3 glory came a long while ago.\r\nBREEDERS' CUP&nbsp;CHALLENGE: Racing schedule, replays, and past winners &raquo;\r\nAfleet Again is winless in eight starts since taking the one-mile Withers in April 2010. He was far behind Birdrun in both the Brooklyn and a May 15 overnight stakes.\r\nYour browser does not support iframes\r\nLikewise, Ron the Greek is 0 for 8 since taking the Lecomte at Fair Grounds in January 2010. His best performance in six starts this year came two races ago, when he earned a 99 Beyer Speed Figure for finishing third in an off-the-turf overnight stakes contested at 1 1/8 miles at Belmont.\r\nChirac earned a career-best 107 Beyer for winning the Iselin over a sloppy Monmouth Park track in 2009. He is intriguing, however, because he is now in the barn of Juan Carlos Guerrero, Parx&rsquo;s leading trainer who is winning at a 40 percent clip. In his first start for Guerrero, Chirac won a $50,000 claimer going a mile, earning a modest 75 Beyer.\r\nThe best recent Beyers in the field belong to Ponzi Scheme, a Monmouth-based 4-year-old who won the Skip Away at his home track with a 103 Beyer two starts ago and an overnight stakes at Delaware Park, good for a 100 Beyer, last time out.