Weekend Surprise's dam Lassie Dear was also the direct female-line ancestor of Duke of Marmalade, Lemon Drop Kid and Ruler of the World.
Kilroy, Summer Squall was trained by Neil J. Howard and ridden by National Museum of Racing and Hall of Fame jockey Pat Day.
They met six times at ages three and four, with Summer Squall winning three of those races, including the Blue Grass Stakes, and finished ahead of Unbridled in one other, the 1991 Pimlico Special.
Running six lengths back, Summer Squall made a move as the field turned into the stretch for home but Unbridled came with him, then pulled away to win.
Summer Squall had bled quite a bit during his racing in Florida and required Lasix to deal with the problem.
Summer Squall went on to win the Grade II Pennsylvania Derby with the use of Lasix, but he bled again while finishing off the board and far back in the Meadowlands Cup.