Di Maestro caught his stablemate Another Softball in the final strides and won by a half length in Friday's fourth race at the Gulfstream Park West meet.
Joe Catanese trains both horses, for different owners.
The race was the start of the Rainbow 6. The carryover coming in was $71,105. Bettors added $27,488 to the pool.
Di Maestro was the 9-5 second choice and Another Softball was the even money favorite in a seven horse field.
The race was a $16,000 maiden claimer at 1 1/16 miles on turf for 3-year-old fillies.
Di Maestro won in 1:47.31 on the course listed as Firm. Jesus Rios rode her for Serena's Dream Catcher Farm. Luca Panici rode Another Softball for owner Renzo Bontempo.