The Aidan O'Brien-trained colt qualified for the $2.2 million Run for the Roses by winning the United Arab Emirates Derby in Dubai but was not allowed to run on the dirt course until he cleared quarantine.
He was passed to run on Friday morning and wasted no time getting warmed up, going for a light trot and gallop around the track under the guidance of his exercise rider Pat Lillis.
The three-year-old colt worked up a sweat in the steamy conditions but O'Brien's head traveling lad T.J. Comerford said he was not concerned about the unseasonally hot weather after winning in Dubai.
"You couldn't be happier with him at the moment," said Comerford.
"He travelled over, he's had two days off and he's well rested. He went out there and he was very professional."
Daddy Long Legs is O'Brien's fourth runner in the Derby. O'Brien has finished no better than fifth in his three previous attempts at the race but faces a tough task this year after Daddy Long Legs drew the number one post position in the 20-horse field.
The last horse to win from the number one post was Ferdinand in 1986 and bookmakers responded by listing Daddy Long Legs at the generous odds of 30-1.
"You don't need to be Einstein to know that it's not a good draw but good horses can win if they're good enough," said Comerford.
"You can't really make a plan. You just ride the horse as he is and hopefully it will work out."
The 4-1 pre-race favourite Bodemeister, who won the Arkansas Derby by nearly 10 lengths, also had a light workout on Friday morning, galloping one a half miles (2400 metres) on the tight oval shaped circuit.
Union Rags, the second favourite at 9-2, completed 1-1/4 miles (2000m), the same distance as the Derby, as did the undefeated Gemologist, who won the Wood Memorial at his last start.
Gemologist's trainer Todd Pletcher, who won the Derby two years ago with Super Saver, also has longshot El Padrino entered in what is looming as one of the most open derbies in decades.
"History tells us that you can't throw anybody out," said Pletcher.
"There have been some winners the past few years that have been way down everybody's depth charts."