Kimi Antonelli faces a Ferrari-shaped threat to his hopes of clinching the Formula 1 world championship in Texas as Lewis Hamilton topped final practice at the United States Grand Prix.
The Scuderia have brought an upgraded package to Austin and it helped Charles Leclerc claim a practice double on Friday.
Hamilton's prancing horse was on top in Saturday's practice session, 0.168 seconds ahead of Red Bull's Max Verstappen with Leclerc in third.
Antonelli claiming the crown in the Lone Star State would be a tall order; he would need to win Sunday's race and hope that George Russell finishes lower than ninth and Hamilton lower than fifth.
The first part of that equation looks set to be a challenge as his rivals showed their prowess in the final running ahead of qualifying.
Antonelli was fourth-fastest after his best lap was deleted for a breach of track limits, one place ahead of Mercedes teammate Russell.
Sunday represents the 20-year-old's first shot at clinching the crown but, with a 102-point lead and only 150 left up for grabs ahead of this weekend's tussle at the Circuit of the Americas, it appears merely a matter of when the Italian becomes champion.
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"Obviously, I'm in an incredible position," Antonelli, who will become the sport's youngest champion, said ahead of the weekend.
"But, of course, I still have to keep going, and the mindset is always the same: whenever I go on track, I want to be at the top and try to win as much as possible.
"Whether I win the championship this weekend, next weekend [Mexico] or in Brazil. Let's see. But it's not over until it's over."
McLaren's Oscar Piastri was sixth-fastest, with Audi's Nico Hülkenberg behind. Piastri's teammate Lando Norris rounded out the top eight.
Qualifying for Sunday's race goes green at 10 p.m. BST / 5 p.m. ET.