Daniil Kvyat is in the frame for a shock return to Formula 1 with the Toro Rosso team that dropped him before the end of the 2017 season.
Kvyat was picked up by Ferrari to work as a development driver after losing Red Bull's support late last year.
Ferrari team boss Maurizio Arrivabene is understood to have met with his Red Bull counterpart Christian Horner and Red Bull motorsport advisor Helmut Marko during the Belgian Grand Prix weekend about the prospect of the 24-year-old rejoining Toro Rosso next year.
It would mark Kvyat's third stint at the Red Bull junior team, having raced there in 2014 and then again in '16 and for 15 races of '17 following a brief spell alongside Daniel Ricciardo at Red Bull itself.
Kvyat's surprise possible recall has emerged because Red Bull currently lacks options for its junior team for next year.
Pierre Gasly will step up to the senior outfit to replace Renault-bound Ricciardo next season, with Brendon Hartley yet to convince Red Bull he is worth retaining for a second full year in F1 following his surprise call-up at Kvyat's expense in 2017.
Red Bull does not have any juniors either ready or qualified to step up to F1 and has been linked with left-field alternatives such as McLaren protege Lando Norris or possible McLaren outcast Stoffel Vandoorne.
Last week, when asked by Autosport about his team's options, Toro Rosso boss Franz Tost said: "There are different names which are being discussed but up to now no decision has been made.
"So therefore we just wait and Red Bull will announce it."
The possibility of another of Ferrari's development drivers, Antonio Giovinazzi, joining Toro Rosso is also understood to be of interest to Red Bull.
Giovinazzi's best shot of a proper 2019 F1 chance was thought to be with Ferrari customer Sauber, as the Italian has tested for both teams this year.
But it is not known if this has been discussed specifically with Ferrari, whereas Kvyat's shot appears more realistic.
Kvyat has had a rollercoaster relationship with Red Bull ever since he joined Toro Rosso for the 2014 season, aged just 19.
He was promoted to the Red Bull senior team as Sebastian Vettel's replacement the following year, but demoted to Toro Rosso again in early 2016.
That came after two high-profile clashes with Vettel and pressure from Max Verstappen's camp to promote the young Dutchman from Toro Rosso.
Red Bull swapped the two drivers and Kvyat struggled to reverse his dip in form during his second spell at the junior team, scoring points in just six of the next 31 races.
He was replaced for the 2017 Malaysian and Japanese races respectively, then scored a point in the United States before that turned out to be just a one-event reprieve.
Kvyat did not compete in the remaining three races of 2017, then secured his Ferrari development role in January this year, which has mainly comprised simulator work and a day of on-track running at Fiorano.