Dr. Samadi (1), the 9-5 favorite, won Gulfstream's fourth race to start Thursday's Rainbow 6.
The carryover coming in was $284,000. Bettors added $126,621 to the Rainbow 6.
Gulfstream guaranteed that the pool will be at least $450,000 if there is just one ticket with all six winners. If that happens, Gulfstream will need to put in about $40,000.
If there are multiple tickets with six winners, Gulfstream will take out 20 percent of the day's Rainbow 6 bet. It will then divide 56 percent among tickets with six winners and add 24 percent to the carryover.
On Saturday, Gulfstream will have a mandatory payout on the Rainbow 6 jackpot (full carryover plus 80 percent of the day's bet), regardless of the number of tickets with six winners.
Dr. Samadi beat Skyline View (9) by 3 1/2 lengths in the $10,000 maiden claiming race for 3-YO and up.
Dr. Samadi won the one mile dirt race in 1:38.51 on the track listed as Fast. Edgard Zayas rode for trainer Mike Maker.
The victory was Zayas's 106th in the Gulfstream spring/summer meet.
Miguel Vasquez is second with 102. He won Thursday's first race, aboard More Diamonds.
Maker has 39 wins in the spring/summer meet, putting him second behind Saffie Joseph Jr. who has 44 victories.
Later this afternoon and this evening, we will have a recap of the Rainbow 6 and other Gulfstream news.