Horner: I don't think F1 racing is on Buemi's agenda

Speaking to Sky F1 after FP2 in Singapore, Horner said of Buemi, "He's an important part of the team. A few other teams have been circling around, interested in the role he's been doing."

"But he's committed to the next three years with the team in the role he's doing. He'll be combining that with his other activities."

"I don't think F1 racing is on his agenda. He has got his Formula E programme, he's got his WEC programme, he does a wonderful job for us in the sim."

"I think that's more than enough for him and he'd have to take a pretty big pay cut to come back into F1," added Horner.

Last week Buemi had a seat fitting at the Toro Rosso factory in Faenza, but he explained that there was not much to it, "I'm just doing what they ask me to do. Of course, if you're the reserve driver you need a seat in case something happens."

"My programmes in the WEC and Formula E are already lined up. Everything is possible but I'm focused on my job here as reserve, and we'll see," added Buemi.

The Red Bull young driver programme currently has no one ready to step up to Formula 1 with their junior team which may force them to seek drivers from other sources.

Currently, Toro Rosso are spoilt for choice as several drivers with unfulfilled potential wait on the fringes including the likes of Daniil Kvyat and Pascal Wehrlein, while Stoffel Vandoorne and Esteban Ocon are seeking a spot on the 2019 grid.