DUBAI, United Arab Emirates -- On paper, Big Orange ranks among the top contenders in the $1 million Dubai Gold Cup on Saturday at Meydan, but his week has gotten off to a rocky start. Out on the Meydan training track Monday morning, Big Orange got upset by something shortly after coming off the horse path and onto the Tapeta oval, and despite the exhortations of his rider, he refused to go forward. Backward, yes, but forward, no. Big Orange appeared to be staring at something down the back-straight and didn't like what he saw. Finally, an outrider came to help, and after several minutes more, Big Orange consented to cantering along with the pony a few paths to his inside. No real harm done there, but after returning to the quarantine facility, Big Orange tied up, trainer Michael Bell told the Racing Post. Tying up, spurred by some metabolic imbalance, is like having a massive muscle cramp, and it's a fairly common issue in racehorses. Bell said Monday he guessed Big Orange would be back to training Tuesday, but Big Orange did not come out to train, instead keeping to the quarantine facility for an easy morning. Bell was due to travel from England to Dubai on Tuesday. Big Orange finished fourth in the 2017 Gold Cup over a rain-soaked course softer than he prefers, and he was a close second here in 2016 while racing on better ground. Big Orange defeated the mighty Order of St. George last summer in the Gold Cup at Royal Ascot. Meanwhile, Vazirabad, winner of the Dubai Gold Cup the last two years, has looked well exercising on the Meydan main track early this week for trainer Alain de Royer-Dupre. Six-year-old Vazirabad’s frame has filled out considerably over the last couple years, and it’s a fair assumption he’ll improve off a second-place finish here March 10 in the Dubai City of Gold. Rare Rhythm, who beat him 1 ¾ lengths in that race, also returns for the Gold Cup.