Fabio Leimer will drive for the Manor team in opening Friday practice for the Hungarian Grand Prix.
The 26-year-old Swiss joined the team as a reserve driver last month, but is yet to drive the car.
Leimer will take over Roberto Merhi's Ferrari-powered MR03B in tomorrow's first practice session.
"Running Fabio in a practice session is a planned opportunity that we have all been working towards for some time," said team boss John Booth.
"We have enjoyed welcoming him into the team over the past few races and it will be interesting to gain his feedback on the car and assess his performance."
Leimer added: "On this most difficult of weekends for the team, I am very appreciative of their decision to continue with my planned FP1 session.
"I'm looking forward to the opportunity and I hope I can make a positive contribution to the engineering programme for the weekend."