Ryan Briscoe will be replaced by Carlos Munoz for the second race of the IndyCar double-header in Toronto after suffering a fractured wrist in a race-one accident.
The Panther driver was running in 12th when Justin Wilson and Charlie Kimball made contact ahead of him, sending Wilson's car into the path of Briscoe's. The injury was caused by Briscoe's steering wheel.
"All of us at Panther Racing hate to see this happen to Ryan, but we've spoken with [IndyCar orthopedic consultant] Dr Terry Trammel and the quick recovery time for this type of injury is very encouraging," Panther boss John Barnes said.
"We all wish Ryan a very speedy recovery and look forward to seeing him back in the National Guard car very soon."
Briscoe will undergo surgery, and could be back in time for the next race at Mid-Ohio.
Munoz's appearance will mark his second career IndyCar start after his sensational second place at the Indianapolis 500 in May for Andretti Autosport.
The current Indy Lights points leader will have the morning warm-up session to prepare for the race, including its planned standing start.
"I have to thank John Barnes and Panther Racing for this opportunity," Munoz said.
"It's unfortunate that it comes as a result of Ryan being injured, but I'm excited about making the most of this opportunity.
"Toronto is a challenging circuit, but just watching practice and qualifications the last few days it's obvious that the National Guard Chevy is fast and I hope to help bring the team a great end to the weekend today."