British Formula 3 championship leader Daniel Ricciardo will make his Formula Renault 3.5 debut with Tech 1 Racing at Portimao next month.
The Australian Carlin Motorsport driver will substitute for fellow Red Bull Junior Brendon Hartley, who is on Formula 3 Euro Series duty with Carlin at Oschersleben.
"It's really Red Bull's decision," Ricciardo told AUTOSPORT. "Brendon is the regular driver but he's not available next weekend and I guess I sprang up in their minds.
"It's a good thing they want to give me a shot and Tech 1 are a championship-winning team so it's a great way to start. I'm not really sure what to expect, but I'm not expecting to be at the back! I hope to give some competition and just compare myself to Charles Pic because he's won races and is quick. If I can challenge Charles, that won't be a bad effort.
"It's also a chance to get in some laps and learn the track before the penultimate round of F3. I'm looking forward to it – it's two long races and it's probably going to be hot so I guess coming from the outback will help!"
GP2 racer Edoardo Mortara replaced Hartley at Le Mans last weekend and finished sixth in race two from 21st on the grid.