Former F1 driver Martin Brundle has insisted Red Bull and an "angsty" Max Verstappen face stiff competition for victory at the Monaco Grand Prix. Ferrari and Aston Martin have targeted the weekend as the first opportunity to topple Red Bull this season after the Milton Keynes-based team stormed to five victories in the opening five races - four of which were secured with one-two finishes. Two-time World Champion Verstappen had a number of gripes in the first session of the weekend, finishing sixth after complaining about the car bottoming out as well as the clutch when leaving his pit box. "The car in high-speed places is unbelievable to drive," said Verstappen over team radio during the session. "I am going to have to box, I am going to shunt with the car set-up like this." Although Verstappen returned to the top of the timesheets in FP2, the rear end of his Red Bull remained lairy, particularly through the second sector from Mirabeau through to Portier. Red Bull will home in on issues Speaking to Sky Sports F1 , Brundle said: "He was angsty even before he got onto the track about the clutch, he wasn't a particularly happy driver at any point [in FP1]. "When the car hits the ground, the load goes through the chassis instead of the tyres, the car is jumping around as well and it is supremely uncomfortable because you are sitting on the floor, effectively, so I understand his issues around here. "The integrity of the suspension now, they don't have too many adjustable parts in there, you don't just put the ride height up and down, it is a package you have to put on now. "It is not an easy fix and he had to live with some problems. "They will home in on where they need to be but they have got some serious competition this weekend."