Looks like Sainz is looking strong in the Williams and could be a championship car for this season as he topped the leaderboard for day 2 of testing:

Bahrain as the name implies had rain which stopped the session but later resumed to finish testing for the day.
Rain In Bahrain! | F1 Pre-Season Testing 2025
https://www.youtube.com/watch?v=LCwI5N3EGv0