Four graded stakes winners, led by recent Brooklyn Handicap hero Birdrun, will challenge defending champion A.U. Miner in Saturday’s $200,000 Greenwood Cup at Parx Racing. The 10 older horses in the 1 1/2-mile Greenwood Cup will be looking to secure an automatic berth in this fall’s Breeders’ 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’ Cup’s Win and You’re In program. Although A.U. Miner got up by a neck to win last year’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’ Cup Marathon, the 5-year-old Birdrun is the logical favorite in Saturday’s race. Based 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. The other Greenwood Cup entrants with a Grade 3 win on their r é sum é are Afleet Again, Ron the Greek, and Chirac. In each case, Grade 3 glory came a long while ago. BREEDERS' CUP CHALLENGE: Racing schedule, replays, and past winners » Afleet 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. Your browser does not support iframes Likewise, 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. Chirac 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’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. The 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.