Brown: "Fernando is very interested in the IndyCar series."

McLaren's CEO Zak Brown has confirmed Alonso's plans for 2019 are still up in the air. Time is starting to become limited for the Spaniard. He may well decide to move to IndyCar full time in pursuit of the triple crown.

Brown also admitted Alonso would be staying in the papaya orange car if they were more successful.

"If we were more successful, he would definitely want to stay in Formula One," Brown said in an interview on Speedweek.

"If you look at the race results, you have to agree with him. He wants to challenge himself, and it could well be that participating in the Indy 500 or the whole IndyCar series would tease and fuel him.

"Fernando is very interested in the IndyCar series. He stands for this championship, but he has not decided yet what he wants to do."

It is sounding increasingly likely that the two-time World champion will be ending his F1 career in just three months time.