At first glance, it might appear that trainer Mike Matz is holding a couple of aces for Saturday’s $75,000 John Rooney Memorial Stakes at Delaware Park with a South American import who finished one length shy of winning a Group 1 race last summer and a horse-for-the-course who has registered 4 wins and a close second in 5 starts over the local turf course.Upon closer inspection, however, one part of Matz’s uncoupled entry, Thundering Emilia, is stuck on the also-eligible list and needs at least one scratch from among the other 14 fillies and mares to get into the field for the 1 1/16-mile Rooney, and his other mare, Aquitaine, has done most of her best racing in claiming and allowance events.Thundering Emilia went 6 for 20 in her native Peru, including a win going 1 1/4 miles on turf in a Group 3 stakes and a runner-up finish, beaten just a length, in a Group 1 event, also at 1 1/4 miles. Five of her six lifetime wins, however, have come on dirt. In addition, she hasn’t raced since September, and Matz is 0 for his last 5 with foreign shippers making their North American debut on turf following such a long break.Matz’s other horse, the 5-year-old Aquitaine, drew unfavorably in post 12. Aquitaine, whose first two career wins came for claiming tags of $30,000 and $20,000, steps up in class following a three-quarter-length victory in a second-level optional $40,000 claimer on May 24. In her lone previous stakes appearance, Aquitaine overcame some early trouble to close for second, beaten 1 1/4 lengths, in last fall’s restricted George Rosenberger.What appears to be a wide-open field also includes Ainamaa, second in last year’s Rooney; La Cloche, runner-up in last September’s Grade 3 Pucker Up at Arlington; Bet On the Blue, third in last month’s Grade 3 Beaugay at Belmont Park; and Apple Charlotte, second in the 2010 Grade 3 Herecomesthebride at Gulfstream Park.Of that group, the best recent form belongs to New York shippers Bet On the Blue and La Cloche.The 4-year-old Bet On the Blue, trained by Hall of Famer Allen Jerkens, has been close in all three starts this season. In addition to her third in the Grade 3 Beaugay on May 7, Bet On the Blue missed by a head at Gulfstream Park and a nose at Belmont last time out, both in overnight stakes.La Cloche, a 4-year-old trained by Jim Toner, returns to stakes company for the third start of her current form cycle after winning a second-level optional $50,000 claimer at Belmont five weeks ago.