The Spaniard secured a slim margin of 0.05 seconds over his team-mate as the Scuderia pair also topped the lap tally, combining to rack up more than 80 laps of data ahead of Saturday’s race.
Sprint race poleman Verstappen, meanwhile, was closer to two-tenths of the leading times but appeared to show the most impressive pace in the long run as the Alpines edged team-mate Sergio Perez.
It was with 25 minutes of the hour remaining that the Ferraris surged to the top of the timing screens as they mounted a set of the fastest C5 soft tires available.
Leclerc buzzed the timing line in 1m08.660s to provisionally sit fastest and would not improve from there as he lost 0.9s over his next few laps to assess the durability of the tire at red sides.
With 18 minutes to go, Sainz set the benchmark for the session, completing the 2.68 mile lap in 1m08.610s to find five hundredths on Leclerc and beat the times.
He was only two laps behind Leclerc, 40 against 42, but will start the sprint race from third place, one place behind his teammate, the Monegasque eclipsed in qualifying by Verstappen late on.
The defending champion finished the session third, falling 0.168 seconds off the fastest Ferrari as Verstappen finished practice at the Red Bull track in 1m08.778s.
Verstappen had set the tone at the start of the session when the focus was on race pace, although the teams were split between targeting the sprint contest or the full grand prix.
Alfa Romeo, Haas and Aston Martin cars ventured first in the hour-long morning race and were joined by Lando Norris’ McLaren, who secured an early tow from Leclerc across the line to post an effort of 1m10.670s on medium tires for the front of the pack first.
Verstappen only joined the action five minutes later, with Red Bull apparently emphasizing sprint racing simulation by running on soft tires while Ferrari kept to medium tyres.
With the advantage of the C5 compound, Verstappen’s first representative effort stopped the clock at 1m09.170s to pass Sainz by 0.3s and Leclerc, then in third place.
Verstappen then lowered it to 1m09.067s to take a four-tenths lead and after being told to hold fifth gear between Turns 6 and 7, dove into the 1m08s with an effort of 1m08.966s.
That put Verstappen 0.2s ahead of Sainz’s best start in the races, with Leclerc 0.6s off the ultimate pace even though his stint average was faster than his team-mate.
Russell entered the session after 11 minutes after ground and gearbox repairs following his Q3 shunt on the final corner, with the Mercedes emerging on soft tires to run third fastest in the races.
He sat in a 1m09.240s, 0.3s behind Verstappen, while separating the Ferrari pair, who then allowed a few mistakes to creep in – Leclerc running away at Turn 3, Sainz locking out at T1.
As Perez continued to miss the fight at the top of the standings, it set the Alpines apart in the overall times as Fernando Alonso and Esteban Ocon swapped places.
It was ultimately double champion Alonso who took the lead, lapping in 1m08.832s to find a narrow 0.16s over Ocon, with Perez finally sixth in 1m09.179s.
The Mexican will start the sprint race from 13th place, having had his Q3 times scrapped for a late Q2 track limit violation that prevented Pierre Gasly from participating in the top-10 shootout for pole race of sprinting.
George Russell, the only rider to adopt the slowest hard tire, placed seventh.
Mercedes team-mate Lewis Hamilton was ninth behind former teammate Valtteri Bottas, with the seven-time champion emerging just 14 minutes behind, a legacy of his heavy Q3 shunt.
Hamilton set just one fast lap on the softs, posting a 1m09.350s to finish ninth ahead of Lando Norris, the McLaren making up for lost time following its brake issues in Q2.
Lance Stroll edged out Gasly, while Sebastian Vettel ran 13th fastest – his session including a run on the jagged pavement at the edge of the final corner to get rid of a piece of carbon fibre.
Zhou Guanyu finished 14th fastest ahead of Mick Schumacher, Alex Albon and Daniel Ricciardo while Kevin Magnussen, Yuki Tsunoda and Nicholas Latifi brought up the rear.