Valtteri Bottas has advantage over Lewis Hamilton in Formula 1 testing

Defending champion Hamilton has completed just 25 laps this week - the fewest by any driver - after Wednesday's third instalment of pre-season testing was effectively wiped out following a deluge of snow and persistent rain.

In contrast to Hamilton's limited running, Bottas already has 152 laps under his belt, the equivalent of two-and-a-half race distances at Barcelona's Circuit de Catalunya.

Mercedes are unsure whether Hamilton will be in their car for the entirety of Thursday's concluding nine-hour test despite amending their schedule to hand Bottas a full day earlier in the week.

"The miles in these conditions are less valuable than proper miles in proper conditions, but I will take it," Bottas said.

"I love to drive as much as possible and I definitely have a better understanding of the car [than Lewis] because of the mileage.

"Lewis however, will soon get a good idea of the new car and he is quick to adapt."

Hamilton, 33, was due to drive on Wednesday but the track was closed for much of the morning with the medical helicopter unable to fly in the torrid conditions.

The circuit opened for business shortly before midday, but all the teams opted against completing any significant running with the high risk of damage to their cars.

Fernando Alonso was the first driver to emerge from his garage as he completed one lap in his McLaren before returning to the pits. His total lap count for the day stood at 11.

Red Bull's Daniel Ricciardo headed out for only two exploratory laps, while Hamilton's Mercedes remained in the garage.

Bottas finished 58 points adrift of Hamilton last season and recorded six fewer victories than his team-mate after spending much of his first Mercedes campaign in the Briton's shadow.

But the 28-year-old Finn is optimistic he can get on top of the four-time world champion when the season starts in Melbourne on March 25.

"Every driver has a weakness, but rather than focus too much on Lewis I am going to spend my energy and focus on myself and my performance on track," Bottas added.

"If I perform on the level I am aiming for at every single race, I hope that will do the job, but I am not going to start wasting my energy on mind games.

"Last year I did not perform on the level I should have and I learned a lot from that. It was tough because I wanted to perform after the August break but I had a few difficult races.

"I have learned massively all through my career as there have been tough times, but that is what makes you stronger and that's how you learn."

The opening pre-season test concludes on Thursday with four further days of practice to take place here next week before the curtain raiser in Australia.