Ferrari’s points leader used his late soft tyre run to turn in a 1m19.772s and he ended the session just seven hundredths in front of his likely end-of-season title rival Verstappen.
But as Carlos Sainz and Sergio Perez struggled to match their respective stablemates, the updated Mercedes W13 continued its impressive showing from Friday as George Russell returned third ahead of his seven-time world champion team-mate Lewis Hamilton.
Replicating his session-topping form from the first and second practice sessions, Leclerc effectively won the opening gambit with his first soft-tyre qualifying simulation.
The Ferrari driver posted a 1m20.278s to sit top after his first attempt but was two tenths slower on his second effort even though he remained in first place ahead of Verstappen and Sainz.
Verstappen did not emerge from the Red Bull garage for a full 25 minutes and at the first time of asking, the Friday race stint pacesetter crossed the line in 1m20.475 on the C3 soft tyre.
Sainz split the Red Bull pair as he ran to third in front of a home crowd, but like Leclerc, the Spaniard ran two tenths slower when he bolted for another soft compound flying run.
Despite Verstappen complaining about the low-speed turn-in of his RB18, his climb to second knocked Russell to fifth - the Brit ahead of the first representative time of the day set by Valtteri Bottas, who missed the bulk of FP2 after an engine shutdown.
Hamilton, meanwhile, was sixth early on but was hobbled by a problem activating his DRS.
The majority of the grid elected for soft tyre runs, and that left Daniel Ricciardo as the fastest C2 medium runner, as the McLaren entered the final 25 minutes of the hour in 12th.
Ricciardo’s team-mate Lando Norris had been the first driver to head out in the session and he immediately delivered a five-lap stint on medium tyres to bed in his new chassis.
The MCL36 had required sweeping repairs after Norris ran wide out of Turn 9 in FP2 to drag his floor over the outside kerbs, the damage having forced the Brit to sit on the sidelines. Similarly, Sainz was sporting a new chassis for his F1-75 following a fuel system issue.
Leclerc then remerged for his second full-tilt run on the soft tyre and duly improved to 1m19.772s to set the eventual yardstick, even if falling a tenth shy of his second practice benchmark.
With his Ferrari’s suspension set-up tweaked, Sainz improved on his second run also to post a 1m20.129s, but nevertheless fell three tenths shy of his team-mate.
Setting adjustments for Russell appeared to pay off handsomely for his next effort climbed him to second initially as he also dipped below 1m20s to deliver a 1m19.920s hot lap.
Sticking to their off-beat run plan, the pair of Red Bulls left it another four minutes until only 13 minutes remained on the clock in FP3 before hitting the track again.
Verstappen immediately demoted Russell as the Dutch racer pumped in a 1m19.844s to sit only seven hundredths shy of Leclerc (who chases a fourth pole in 2022) in second.
Perez, however, could only manage a 1m20.260s to fall behind Sainz in sixth thanks to Hamilton’s improvement to fourth on a 1m20.002s, running 0.09s shy of Russell - who had nabbed the best first sector of the session - with 10 minutes to run.
Behind Sainz and Perez, Norris effectively claimed the ‘best of the rest’ accolade as he ran to seventh courtesy of a 1m20.403s effort to sit ahead of Kevin Magnussen and Bottas.
Esteban Ocon, meanwhile, completed the top 10 ahead of Ricciardo, with the charge of the controversial and heavily updated Aston Martin AMR22 led by Sebastian Vettel in 12th.
Fernando Alonso ran to 13th over Zhou Guanyu and Yuki Tsunoda, the AlphaTauri driver having notably clattered over the Turn 15 kerbs to briefly launch into the air.
Lance Stroll topped the Williams of Alex Albon and Nicholas Latifi.
Both Mick Schumacher and Pierre Gasly wade into qualifying with damp powder after a heavily truncated final practice session.
Gasly was forced back into the pits at the end of his installation lap with a fire, which was attended to by AlphaTauri, but he never returned to the track aboard his AT03.
After just four laps on the medium tyre, Schumacher endured a similarly smoky fate when flames began to shoot from his rear-right brake assembly inside the wheel rim.
While he returned to the Haas garage, where the front jack mechanic was knocked over, and the fire extinguished, it transpired that the rear-left corner was also scorched.
F1 Spanish Grand Prix - FP3 results
| Cla | Driver | Chassis | Engine | Laps | Time | Gap | |
|---|---|---|---|---|---|---|---|
| 1 |  Charles Leclerc |  | Ferrari | Ferrari | 23 | 1'19.772 | |
| 2 |  Max Verstappen |  | Red Bull | Red Bull | 12 | 1'19.844 | 0.072 |
| 3 |  George Russell |  | Mercedes | Mercedes | 16 | 1'19.920 | 0.148 |
| 4 | Lewis Hamilton |  | Mercedes | Mercedes | 18 | 1'20.002 | 0.230 |
| 5 |  Carlos Sainz |  | Ferrari | Ferrari | 23 | 1'20.129 | 0.357 |
| 6 |  Sergio Perez |  | Red Bull | Red Bull | 19 | 1'20.260 | 0.488 |
| 7 | Lando Norris |  | McLaren | Mercedes | 18 | 1'20.403 | 0.631 |
| 8 |  Kevin Magnussen |  | Haas | Ferrari | 21 | 1'20.646 | 0.874 |
| 9 |  Valtteri Bottas |  | Alfa Romeo | Ferrari | 24 | 1'20.781 | 1.009 |
| 10 |  Esteban Ocon |  | Alpine | Renault | 18 | 1'20.882 | 1.110 |
| 11 |  Daniel Ricciardo | | McLaren | Mercedes | 17 | 1'20.910 | 1.138 |
| 12 |  Sebastian Vettel |  | Aston Martin | Mercedes | 24 | 1'20.944 | 1.172 |
| 13 | Fernando Alonso |  | Alpine | Renault | 17 | 1'20.981 | 1.209 |
| 14 |  Zhou Guanyu |  | Alfa Romeo | Ferrari | 19 | 1'21.201 | 1.429 |
| 15 |  Yuki Tsunoda |  | AlphaTauri | Red Bull | 22 | 1'21.449 | 1.677 |
| 16 |  Lance Stroll |  | Aston Martin | Mercedes | 23 | 1'21.520 | 1.748 |
| 17 |  Alex Albon |  | Williams | Mercedes | 18 | 1'21.572 | 1.800 |
| 18 | Nicholas Latifi |  | Williams | Mercedes | 18 | 1'22.419 | 2.647 |
| 19 | Mick Schumacher |  | Haas | Ferrari | 4 | 1'25.467 | 5.695 |
| 20 | Pierre Gasly |  | AlphaTauri | Red Bull | 1 | ||
| View full results | |||||||
