Led by Animal Kingdom, the winner of the Kentucky Derby, an intriguing mix of Derby participants and Triple Crown newcomers is set to be entered Wednesday in Saturday’s 136th Preakness Stakes at Pimlico Race Course in Baltimore, but the final composition of the field was still in flux Monday, owing to the difficulty owner Ahmed Zayat was having deciding on whether to run Nehro, the Derby runner-up. Nehro worked a half-mile in 50.80 seconds on a sloppy track Monday morning at Churchill Downs, and Zayat flew in to watch him. A few hours later, Zayat said he would not decide what to do until Tuesday. Immediately following the Derby, Zayat seemed far more inclined to await the Belmont Stakes, the final leg of the Triple Crown, on June 11. But he’s torn now on whether to come right back in the Preakness. “The horse is telling us he is ready,” Zayat said. “My brain can’t accept four hard races in eight weeks.” PREAKNESS STAKES 2011: Contender profiles, news updates, video and odds » Nehro has finished second in the Louisiana Derby, Arkansas Derby, and Kentucky Derby in his last three starts. Should he run in the Preakness, that would be his fourth start in eight weeks. Zayat said he wanted to take a day to “let it sink in.” He said he would make the decision in consultation with Steve Asmussen, who trains Nehro. “It is such a tough decision,” Zayat said immediately following the work. “I know what I saw. I saw a significantly better work than what I saw before the Derby. He looked beautiful out there – his leads, his head. I saw what I wanted to see. I will talk to my team and I will weigh the benefits, and then we will make a decision.” As of Monday, 16 3-year-olds were under consideration for the 1 3/16-mile Preakness, which has a maximum field of 14. If those 16 are entered Wednesday, the two who would be excluded from the race would be Isn’t He Perfect and Saratoga Red, in that order. Unlike the Kentucky Derby, which simply uses earnings in graded stakes races to determine starters in an oversubscribed field, Pimlico uses a convoluted, three-tiered system for the Preakness that earmarks the first seven spots based on graded earnings, then has two different criteria for the next sets of runners. In addition to Animal Kingdom and Nehro, the Derby alumni pointing to the Preakness are Mucho Macho Man (third in the Derby), Shackleford (fourth), Dialed In (eighth), and Midnight Interlude (16th). The new shooters who would make the 14-horse field are Astrology, Concealed Identity, Dance City, Flashpoint, King Congie, Mr. Commons, Norman Asbjornson, and Sway Away. Astrology, also trained by Asmussen, worked Monday morning at Churchill Downs and went an easy half-mile in 51.60 seconds. Midnight Interlude also worked at Churchill Downs, traveling three furlongs in 35.60. “He went very nice, with a lot of energy,” said his trainer, Bob Baffert, who was at Churchill Downs for the work. “It was probably his best work over the track since we got here.” Victor Espinoza rode Midnight Interlude in the Derby, but Martin Garcia will be aboard for the Preakness, reuniting the jockey-trainer combo that captured last year’s Preakness with Lookin At Lucky. Baffert said Midnight Interlude’s performance in the Derby was “very puzzling.” “He broke well, but Victor said as soon as horses came over top of him, he hated it and he lost all interest,” Baffert said. “He ran 16th, but this is only a 14-horse field, so no matter what, he’s going to improve.” Midnight Interlude is scheduled to fly to Baltimore on Wednesday on a charter flight from Louisville, Ky., that would also include Astrology, Dance City, Dialed In, Flashpoint, Mr. Commons, Nehro, Shackleford, and Sway Away. Mr. Commons was scheduled to travel from California to Kentucky on Tuesday, then continue on to Maryland on the Wednesday flight. Entries for the Preakness are due Wednesday morning at Pimlico, and the draw will be held at the track later that day beginning at 5 p.m. Eastern time. The draw will be televised live by HRTV. Since Bally Ache returned to win the Preakness after finishing second in the Derby in 1960, only two Derby runners-up have won the Preakness – Summer Squall in 1990 and Prairie Bayou in 1993. Pimlico linemaker Frank Carulli said he intends to set Animal Kingdom as a tepid favorite on his Preakness line, with Nehro “no worse than second choice if he runs.” Mike Watchmaker, Daily Racing Form’s national handicapper, on Monday said he would make Animal Kingdom the 5-2 choice if Nehro runs and would lower Animal Kingdom to 2-1 if Nehro is out of the race. Animal Kingdom is at the Fair Hill training center in Maryland with trainer Graham Motion and will not arrive at Pimlico until later in the week. “It’s where we are comfortable,” Motion said. “It’s a relaxing atmosphere for him.” Animal Kingdom is not scheduled to have a workout in between the Derby and Preakness. The weather forecast for Baltimore calls for showers and thunderstorms all week, with the highest probability from Tuesday through Thursday, according to the National Weather Service. Saturday’s forecast is for a 40 percent chance of showers and a high temperature of 81 degrees. – additional reporting by David Grening and Marty McGee