Red Bull's Sergio Perez set the pace once again in free practice in Austin, the Mexican showcasing his car's improvement as he edged Ferrari's Carlos Sainz and teammate Max Verstappen.
McLaren's Lando Norris clocked in fourth, leading the Mercedes duo of Valtteri Bottas and Lewis Hamilton in P5 and P6.
Saturday in Austin dawned warm and sunny once again, but the 28°C weather was hardly an incentive to encourage drivers to hit the track when the light went green at the end of the pitlane.
As a reminder, Friday's benchmark time was sent in FP1 by Bottas with a 1m34.874s flyer.
The healthy crowd had to wait a few minutes before it greeted the first driver which was Aston Martin's Sebastian Vettel. The German was followed by Alpine's Fernando Alonso but as usual, the start of the session was devoted to installation laps.
Fifteen minutes in, the track finally started to populate, but laps remained largely irrelevant until Hamilton pumped in a 1m35.814s on the soft tyre, but the Mercedes driver was quickly outdone by Perez.
Minutes later, Verstappen - also on the softs - popped to the top with a 1m34.912s that put him 0.296s clear of his teammate and 0.659s ahead of Hamilton, with Leclerc and Sainz further behind.
Onboard footage showed a very stable RB16B compared to Friday, a change that pointed to overnight improvements in the Red Bull camp.
After having his best time deleted for exceeding track limits - a key theme in the session - Bottas pushed on and slotted himself between the two bulls.
But a flyer from a soft-shod Sainz saw the Ferrari driver jump ahead of all of his rivals to take the top spot, while Norris progressed to third.
As the session entered its final 15 minutes, drivers ramped up their qualifying simulations, which led to Perez reclaiming first place, 0.104s ahead of Sainz.
But positions at the top were tight with just 0.287s separating the top 5.
A final push by Verstappen was thwarted by a slow-moving Antonio Giovinazzi, but Red Bull concluded the final dress rehearsal before qualifying at the top of the firld, thanks once again to Perez.
Positions among the top four remained unchanged with Sainz, Verstappen lining up behind Perez, with Bottas and Hamilton concluding the session P5 and P6.
Thereafter followed Ricciardo, Gasly, Leclerc – who spent the latter part of FP3 struggling with his rear tyres – and Ocon.
Red Bull have clearly raised their game since Friday, but will it be enough to counter the inevitable onslaught from the Mercedes camp?
Check back in a few hours to find out.
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