Spa-Francorchamps - Red Bull chief Christian Horner revealed on Friday that the team demoted Pierre Gasly to spare the driver from the pressures of racing against Max Verstappen in a front-running outfit.
Horner said Frenchman Gasly was struggling to handle the challenge and, after a poor weekend at the Hungarian Grand Prix, the team needed to take action.
"We took a bit of time to reflect after Hungary," said Horner.
"We came to a conclusion that it was almost fairer for Pierre - and from a team perspective - to say 'we're in a unique position with four cockpits in F1 so let's take the pressure off him'.
"He was obviously struggling with that pressure. The situation was getting worse and worse and compounding itself so we decided to give him time to rebuild himself at Toro Rosso and to give Alex (Albon) the chance."
Horner told Sky Sports that Russian Daniil Kvyat, in consistent form this year with Toro Rosso, was a candidate for promotion, but they wanted to see how Albon coped with the role as team-mate to Verstappen in the senior outfit.
"We know Danny Kvyat," said Horner. "We know him very well and we see his potential, but with Alex we've seen his potential as well with the simulator running he's been doing.
"So we chose to take these nine races to evaluate him between now and the end of the year and to decide who's going to be Max's team-mate next year."