McLaren and Toro Rosso are holding last ditch talks to try and agree which engine manufacturer they will both use during the 2018 season, with a decision between Honda and Renault expected on Monday.
McLaren are keen to get out of their deal with Honda and switch to Renault, but that would require Toro Rosso to agree to a swap from current supplier Renault.
Although Toro Rosso team principal Franz Tost recently stated that discussions with Honda weren't serious, it's believed efforts have been ramped up this weekend with Red Bull leading negotiations on behalf of its junior team.
McLaren is pushing for that deal to happen, which would open the door for it to take up the Italian outfit's Renault deal as the FIA states that no manufacturer can supply more than three teams.
Whilst the FIA could allow some dispensation by giving Renault permission to supply a fourth team, that would push Honda out of the sport, something the FIA and Liberty Media is very keen to avoid when manufacturer interest is at an all-time low.
It's believed Red Bull and Toro Rosso have set a Sunday evening deadline for an agreement to be reached, which has prompted Honda motorsport boss Masashi Yamamoto to fly out to Monza on Saturday to discuss the matter, following a meeting with Honda's board in Japan this week.
