Baku - Brendon Hartley is expecting Fernando Alonso to be "pretty tired" as his split duties between F1 and Le Mans racing kick off.
Spaniard Alonso is already at Spa Francorchamps, where at the weekend he will begin his adventure racing for Toyota in the world endurance championship.
'It will be something different'
Last year, now Toro Rosso driver Hartley did a similar thing, getting the call-up to race in F1 while completing his sports car duties for Porsche.
The New Zealander told Spain's El Mundo Deportivo: "It will be something different for him. "I did a similar thing to him at the end of last year. It's exciting but he'll be pretty tired when everything's over.
"I don't know how many consecutive weeks he has, but I would say that Le Mans is a very exhausting race. It's not just a weekend, it's a full week, there's a lot of preparation, very short nights.
"But I think he'll love it."