Dale Coyne Racing replaced Carlos Huertas on the opening day of the Long Beach Grand Prix with a driver who will be making his IndyCar Series debut.
No reason was given for the change to Rocky Moran Jr., a 35-year-old who last raced in 2011.
Despite the lack of experience in an Indy car, Moran was nearly 1.5 seconds faster in Friday's practice than Coyne teammate Francesco Dracone.
Dracone, the slowest driver in the first two races of the season, was fined $10,000 for hitting a crew member on pit road at New Orleans.
Moran last competed in five ALMS races in 2011. He ran in the Grand-AM Series in 2006, and the Indy Lights race at Indianapolis Motor Speedway in 2005. He's a multiple race winner in Toyota Atlantic.