Red Bull is closing on a deal to place newly-crowned GP2 champion Pierre Gasly in the Japanese Super Formula series next season.
Gasly overcame a strong challenge from Prema teammate Antonio Giovinazzi to clinch the GP2 crown in the final round of the series at Abu Dhabi last month.
But with both Red Bull and Toro Rosso's seats for 2017 having been locked down, his success has come too late to help him make the move up to F1.
Instead, Gasly is set to switch to Super Formula, where McLaren's Stoffel Vandoorne raced successfully this year, with Red Bull having already entered into discussions about finding a berth for the Frenchman.
Motorsport.com understands that talks with Honda about placing Gasly with one of its teams, Nakajima Racing, have stalled, and that Red Bull is now in discussions with Toyota about arranging a drive.
While the TOM'S line-up of Kazuki Nakajima and Andre Lotterer is set to remain unchanged, Team Le Mans, which ran Narain Karthikeyan and Kamui Kobayashi this season, is a possible option for Gasly as neither of its existing drivers are expected to return.
Talks between Toyota and Red Bull are thought to be at an advanced stage.
Horner: Gasly still has F1 future
Speaking in Abu Dhabi, Red Bull team boss Christian Horner praised the job that Gasly had done in GP2 this year, and made it clear that he was still very much on the team's radar for a future in F1.
"I think Gasly has done a great job this year," said Horner. "It is good to see him win the GP2 championship.
"He has done important work for us with tests and development work. There isn't a seat available in F1 for him at the moment, but he is the most senior member of the junior team and is being retained by us because we rate him extremely highly.
"Whatever the future holds for him, F1 can still very much be part of that future."
Additional reporting by Kunihiko Akai