Kentucky Derby winner Justify won the Preakness Stakes on Saturday and is on course to become the 13th horse to win US flat racing's Triple Crown.
Unbeaten in five starts, Justify can complete the coveted treble at the Belmont Stakes on June 9.
The Bob Baffert-trained Justify, ridden by Mike Smith, was pressed all the way by Kentucky Derby runner-up Good Magic.
But the 1-2 favourite had enough at the end to seize the victory before a crowd of 134,487 at Pimlico in Baltimore.
"Oh man, it was a nail-biter," said Baffert, whose seventh Preakness victory saw him tie 19th-century trainer Robert Wyndham Walden for the all-time record.
Baffert also matched D Wayne Lukas's record of 14 victories in the Triple Crown races -- the Kentucky Derby, Preakness and Belmont Stakes.
It was Baffert who saddled American Pharoah in 2015 when the three-year-old became the first horse in 37 years to win all three.