Antonelli is currently competing in his first season of F2 as his racing education as part of the Mercedes development programme and, with Lewis Hamilton leaving at the end of the season and heading to Ferrari, the Italian has been one of the drivers linked to the vacant seat alongside George Russell.
But speculation that Antonelli could replace Sargeant this season gathered pace during the Miami Grand Prix weekend after the FIA received a request to waive the superlicence minimum age requirement, given the Italian is yet to turn 18.
Sargeant has endured a disappointing start to the season, hampered by an underperforming Williams, as well as being forced to miss the Australian Grand Prix when team-mate Alex Albon took over his chassis after damaging his own beyond repair.
After Mercedes boss Toto Wolff shut down this speculation saying the early progression is "not something we have pursued", when asked whether he felt any pressure from the uncertainty over his race seat, Sargeant said: "I'm just doing my job the best I can.
"I feel like, I mean, jumping in FP1 this weekend the most comfortable I felt all year and I feel like I was straightaway on it.
"If I look since Australia, I feel like it's been going relatively well, from a pace front. Japan, getting almost everything out of it. Of course, China was disappointing, but again here [Saturday at Miami], I feel like I did a good job. So... just looking for that last tenth. But nonetheless, just enjoying it, being home and keep delivering the best I can."
Sargeant was taken out of his home race in Miami after contact with Haas driver Kevin Magnussen, which resulted in the race-defining safety car period that saw Lando Norris jump into the lead.
Asked if there had been discussions with Williams team principal James Vowles over the security of his seat, Sargeant replied: "No, I wouldn't say. I wouldn't say so, no. I talked to James internally. I talked to my managers.
Pressed on whether he was given assurances from Vowles, the American added: "That's all internal talk. I'm not gonna say anything."
