Sebastian Vettel says it's impossible to know what role tires will play in Monaco this weekend until the teams have done some running.
The consensus is that Mercedes will be quick in qualifying once again, but how that might pan out in the race is hard to predict.
"People make out that Mercedes is the favorite," said Vettel. "Obviously they had a very impressive speed in the last couple of races, and as we know in Monaco it's very important to qualify in the front.
"It's a bit difficult and unknown at this stage how important the tires will be, especially how long they last. If they last well, then they won't be very important. If people are running into trouble, then it could be that pole is not everything.
"But, for sure, it's not a secret: around here you need to have clear laps and no traffic because overtaking is quite difficult. I still think that everyone is shooting for pole, and as I said in the last couple of races, Mercedes was very strong. If we get into the groove nicely, and fine the rhythm, which I think is very important around here, then we should have a good chance. How good our chances are right now, I can't say. I think we need to get into the car tomorrow and get a first view."
Vettel, who won at Monaco in 2011, made it clear that it's a special event for him.
"It's a very emotional Grand Prix," he said. "History is very popular around here. Just looking around I think it's spectacular. Every year you come back and it's one of the greatest Grands Prix we have. In terms of racing and overtaking it's probably the worst place you can think of.
"Still it's a fantastic Grand Prix, it's exciting to race through the city, the circuit is very technical. The driver here I think is more important than in other places. That's why as I said it's important to get into the rhythm, be confident with your car. To win here, for sure, does taste sweeter than anywhere else."