Seventh choice Big Week stole the last jewel in the Triple Crown, winning the 71st Kikka-sho over the Yutaka Take-ridden favorite Rose Kingdom on Sunday.
Under first-time Kikka-sho winner Yuga Kawada, Big Week turned for home stalking pacesetter Cosmo Laputa before moving clear halfway down the final straight at Kyoto Racecourse.
Big Week held on to the lead for a 3 minute, 6.1 second victory in the 3,000-meter Japanese St. Leger, finishing a length and a quarter ahead of the incoming Rose Kingdom.
Beat Black, the 13th pick in a full field of 18, took third a further neck behind.
"I thought for sure we'd have our chance," Kawada said. "I pushed him like crazy because there are a lot of tough horses in the field. But he stuck it out."