Red Bull's Max Verstappen took his first Monaco Grand Prix pole position on Saturday with a breathtaking final lap to deny Aston Martin's Fernando Alonso the crucial top slot. Alonso will start alongside on a front row of double Formula One world champions with Ferrari's home hero Charles Leclerc unable to secure his third Monaco pole in a row and having to settle for third. "You have to go all out and risk it all," said Verstappen after the session. "I knew I was behind, I'm very happy to be on pole for the first time here." The session was red-flagged when Sergio Perez smashed his Red Bull into a wall leaving last year's winner at the rear of the grid. With overtaking at a premium on the narrow streets of the principality, Perez's misfortune could prove costly for his title challenge with the Mexican 14 points adrift of Verstappen going into this sixth race of the season. Carlos Sainz in the second Ferrari posted the fifth fastest time to occupy the third row with Mercedes' Lewis Hamilton. Ocon's Alpine teammate Pierre Gasly, George Russell of Mercedes, Alpha Tauri's Yuki Tsunoda and McLaren's Lando Norris completed the top 10. Alonso's Aston Martin mechanics celebrated wildly after it appeared as though the 41-year-old Spaniard had taken his first pole in 11 years. But Verstappen delivered a mesmerising final sector in Monte Carlo to take top spot with his final charge, beating Alonso by just 0.084 seconds. Mercedes were banking on their much-anticipated upgrade providing them with a springboard to challenge the grid's all-conquering Red Bull team. But on its grand unveiling in Monaco, Hamilton was at odds with his new machine. The British driver, who crashed out of final practice following a mistake at the right-hander Mirabeau, missed the chicane in Q1, only avoiding an early bath with his final lap, before scrambling into Q3 after he grazed the wall at the swimming pool chicane. "Man this car is hard to drive, mate," said the seven-time world champion, who also reported there was "something wrong" with his right-rear suspension. Alonso walked over to Verstappen and shook his hand after a tight tussle between the two-time F1 champions. “Feels great, I always had confidence in what I could do," Alonso said. “We’re starting on the front row in Monaco, so job done." Alonso has four third-place finishes in five races, so Verstappen joked that he’d try to help him finally win again. “I’ll think about it. I’d like to see Fernando win, but I’d like to win myself,” Verstappen said. “I love watching his style." Later in the day, Leclerc was demoted three places on the grid for Sunday's race after the race stewards ruled he had impeded another driver at the end of qualifying. Leclerc, a Monaco native, was found to have blocked McLaren's Lando Norris during qualifying. Frenchman Ocon in an Alpine, moved up to third on the grid while Spaniard Sainz, in the second Ferrari, was promoted to the second row and Hamilton in a Mercedes moved up to fifth.