Australian import Leonidas, making his Grand Circuit debut after impressive performances in the Open Handicap at Yonkers Raceway, sat back off a wicked pace and then rallied powerfully in the lane to win the fifth edition of the $100,000 Potomac Pace for free-for-allers on Sunday night at Rosecroft Raceway.  The final time for the 15-1 winner was a career-best 1:48 flat. The field of nine was reduced by two as Breeders Crown Open Pace champion Century Farroh, along with Highlator, were both scratched sick.  With those two horses not in the event, the pace in the Potomac was provided by another Australian-bred in Stars Align (Corey Callahan), who rocketed to the lead from the outside post seven and ripped off an opening quarter in 25 1/5, the fastest in track history.  This Is The Plan (Yannick Gingras) came to the outside from the pocket before the quarter went on the board, but quickly relented and settled back into the two-hole. Stars Align continued to have the pedal fully depressed after that, as he reached the half in 52 4/5.  Backstreet Shadow (Tim Tetrick) came first-up from third going to that marker, with 1-5 choice Bettor's Wish (Dexter Dunn) coming out second-over and Harambe Deo (Simon Allard) positioned third-over.  Leonidas and driver Austin Siegelman were last and elected to sit in, saving some ground and gaining some positions. Backstreet Shadow advanced into second at three-quarters, which was posted in an incredible 1:19 3/5, and Bettor's Wish looked poised to strike as he was still sitting second-over.  Behind Bettor's Wish, Harambe Deo had not been able to keep up to the cover, and that allowed Siegelman and Leonidas to slip out third-over prior to three-quarters. On the far turn, Bettor's Wish was sent three-wide as Backstreet Shadow had been rebuffed by Stars Align and was stalled out, and Leonidas tracked that move.  Bettor's Wish was able to get around Backstreet Shadow to take over a two-wide position late on the bend, and then he would vault past Stars Align in upper stretch.  Though Bettor's Wish had the jump and command, he was under steady urging after he made front, and Leonidas pounced three-wide, out-kicking the public choice on his way to winning by three-parts of a length.  Bettor's Wish had to settle for second, and World Of Secrets (Aaron Merriman) rallied up the inside for third at 59-1.  Stars Align, This Is The Plan, Backstreet Shadow, and Harambe Deo rounded out the order. "He was just getting going in the stretch.  He's a stone-cold closer.  Each time I've driven him, he's never gotten tired," said Siegelman.  "I got really lucky that Harambe Deo gapped and I was able to slip out.  After that I thought I was going to have the race won.  I thought I might be trouble going up the inside when I saw the half and everything that was going on.  I figured the front-end was going to fold, but I was able to slip out in time, and it worked out. "It's a great feeling.  I've never won a race like this before, so I'm just trying to take it in." Sheena Mcelhiney trains Leonidas, a 5-year-old gelding by Mach Three, for owner Jesmeral Stable.  This was his 24th career win, and he has now earned $216,848.  He paid $33.20 to win. "We're obviously really excited to be here.  It was little bit of an unexpected invite, but the way he raced at Yonkers last week, we thought we had a pretty good shot coming into it," remarked Mcelhiney.  "It was a little daunting hearing who was going to be in the race with him, but I think he did well tonight, and we're pretty impressed with him.  Last week at Yonkers he had a back-half of 53 1/5 and a last quarter of 26 4/5.  It's pretty impressive.  He's definitely not a front-runner, but I think he's just improving every week, and he's getting used to the style of racing here because it's a little different overseas.  Every week he just seems to get better and better. "It definitely feels good.  It's kind of just sinking in right now because we haven't had him too long.  We're still just kind of figuring him out at this point.  We definitely look forward to the future and look forward to more races like this with how he raced tonight."