Singapore, Sep 16 : Ferrari's Carlos Sainz once again topped the timesheets in Free Practice 3 for the F1 Singapore Grand Prix, with Red Bull's Max Verstappen only fourth after once again complaining of wheelspin and rear instability. Sainz and Charles Leclerc had topped both of Friday's practice sessions, with the Prancing Horse looking like the team to beat ahead of qualifying later on Saturday. By contrast, Verstappen seemed unable to match the Ferraris' pace, and he radioed his team several times throughout the session to complain about his upshifts, which he said were giving him wheelspin, reports Xinhua. A trip to the pits late in the hour seemed to partially solve the issue, but the Dutchman said his RB19 was still sliding at the rear, and he ended the session 0.313 seconds adrift of Sainz's best time of 1:32.065. Behind Sainz, George Russell finished second in his Mercedes, 0.069s behind the Spaniard, with McLaren's Lando Norris ending the session third to ensure that the first four spots were filled by four different teams. Verstappen is followed by Leclerc, who might well have been higher had he not aborted his final qualifying spin after running wide over a kerb. Verstappen's high-fuel race simulation runs earlier in the session seemed to be more consistent, but qualifying is of paramount importance at Singapore due to the difficulty of overtaking at the Marina Bay Street Circuit, and with Red Bull teammate Sergio Perez only eighth in FP3, Red Bull's flawless win record so far in 2023 may be under threat this weekend. Further, down the field, Aston Martin will likely be disappointed with Fernando Alonso and Lance Stroll finishing the session 13th and 14th on a track where the AMR23 was expected to be strong, while China's Zhou Guanyu ended up 19th on a circuit that was not expected to suit his Alfa Romeo C43. /IANS