Renault has played down the chances it might supply engines to McLaren next year.
As the British team struggles with Honda, Mercedes and Ferrari have already made clear they will not be leaping to McLaren’s rescue.
So at Spa, rumours emerged that if McLaren does split with Honda, the only option could be Renault.
"I can confirm that there has been discussion with McLaren," said Renault chief Cyril Abiteboul.
The spanner in the works, however, is that FIA regulations forbid manufacturers from supplying to more than three teams — and Renault is fully subscribed with its works team plus Red Bull and Toro Rosso.
Of course, a Renault deal would be freed up if Toro Rosso makes the switch to Honda — and that would also keep the Japanese carmaker in F1.
"It doesn’t really affect us whatever engine Toro Rosso takes," said Red Bull’s Christian Horner. "We just need to know pretty quickly what the situation is — within the next couple of weeks."
For its part, McLaren is therefore pushing hard for a Toro Rosso deal and even willing to produce a gearbox for the junior Red Bull team.
But if Toro Rosso doesn’t make the switch, Renault advisor Alain Prost says it is "impossible" that a McLaren-Renault deal can happen.
"As McLaren have problems with the Honda engine, they asked us," Prost told the Belgian news agency Sporza.
"But it’s impossible for Renault to have another team."