However, Antonelli pushed his Mercedes too far at Parabolica, with his car crashing into the barriers and ending his first session prematurely.
Despite the mistake, team boss Toto Wolff remained confident in his star, as the team announced Antonelli’s signing on Saturday.
Have Mercedes made the right decision with Kimi Antonelli?
Whilst Mercedes were one of the last teams to announce their 2025 line-up, Wolff claims that they have had their mind made up for a while in a shock admission.
"I made up my mind five minutes after Lewis Hamilton told me that he's going to Ferrari," Wolff said to Autosport.
"Obviously, we were discussing other options, and also kept the Max idea. We didn't discount it completely with looking at what happened at Red Bull, but instinctively, that is the line-up with these two that I always wanted.
"Bearing in mind the fast-tracking that we did with Kimi and everything related there too, but that was immediately what I wanted to do.”
Antonelli has enjoyed a rapid rise through the junior ranks, bypassing Formula 3 and heading straight to Formula 2, where he has won two races at Silverstone and Hungary.
"These two are the future,” Wolff added.
“They have been and will be Mercedes drivers, and therefore we have contracts with George and Kimi that go much longer, that are very complicated in terms of options, etc.
"This is a pressure cooker, but this is where we stand as a team today, we want to go with these two.
“The most important thing is to see how George and Kimi settle in and I see no reason at that stage not giving them the faith and the trust of going forward.
"What that means for the terms is something that we will discuss between ourselves, but we wouldn't have gone for the line-up with these two if we wouldn't believe 100% that they are the best choice for Mercedes."