British Grand Prix winner Sainz lapped the Hungaroring with a quickest time of 1:18.750, with championship leader Verstappen 0.130 slower on a track expected to favour Ferrari.
Ferrari's Charles Leclerc (24), the Dutch driver's closest championship rival despite being 63 points adrift after crashing out while leading in France last weekend, was third and 0.289 off the pace.
McLaren's Lando Norris (22) was fourth on the soft tyres, ahead of Mercedes' George Russell (24) and Red Bull's Sergio Perez (32) who complained over the radio of "a bit of an allergy" after suffering a very public sneezing fit at speed.
Seven time world champion Lewis Hamilton (37), a record eight time winner in Hungary, was seventh fastest for Mercedes but 0.960 off Sainz's time.
Aston Martin experimented with an eye-catching new rear wing, and had Sebastian Vettel (35) - who announced his impending retirement at the end of the season - 11th fastest a day after the four times world champion announced his retirement at the end of the season and team mate Lance Stroll (23) 12th.
Haas also rolled out an updated car for Denmark's Kevin Magnussen (29) with some striking aerodynamic similarities to the Ferrari.
Sunday's race is the 13th of 22 this season and last before the August break, which you can follow with Flashscore across the whole weekend.
