Daniel Ricciardo has weighed in on the tyre degradation debate, saying it is so bad that cars are shooting up "rubber pellets".
Pirelli changed their compounds ahead of this season with the aim of creating more degradation and spicing up the show.
However, in the cold temperatures experienced so far in pre-season testing, the degradation has proven to be severe.
"They're providing a challenge, definitely," Ricciardo told ESPNF1.
"It's still obviously early days and conditions are very cool - we probably won't come across many of these conditions during the racing calendar - but they're challenging at the moment.
"I'm not sure if they're doing what they thought they would or what they were expecting, but some of the working ranges for the tyres have changed this year - I think they all have actually - and maybe we're just not reaching the working range to really see what they tyre's supposed to do.
"It's still early, but let's say for example today was quite a challenge because there were quite a bit of marbles and stuff as well. Particularly some guys on long runs that I came behind it's like they're shooting rubber pellets at me!"
The Toro Rosso driver, though, says there is no point in getting upset about the situation as he expects it will improve come the Australian GP.
"I think it's important now to just not get frustrated or definitely not be negative about anything because I think once racing starts it's going to be a different story.
"It doesn't hurt to be quick here; I would like to be P1 but it's not really the aim.
"It's gone quick, it feels like testing hasn't really started as soon as it's finished but I'm happy to go racing and I'm sure that once we're in Melbourne we're going to be more than ready to attack and hopefully start the season on a high."