McLaren have taken a significant step forward and Mercedes no longer have the quickest car in Formula One, championship leader Kimi Antonelli said after the Dutch Grand Prix at Zandvoort.

McLaren's reigning champion Lando Norris celebrated his second consecutive win from pole position on Sunday, with Antonelli and Mercedes teammate George Russell finishing second and third. Ferrari's Lewis Hamilton and Charles Leclerc completed the top five.

"We're clearly not the fastest car any more on the grid," said Antonelli, who won five races in a row earlier in the season. "We're probably second or third, at least in today's race, and McLaren has taken a huge step, especially since Hungary, since the big upgrade package they brought."

However, Norris, who lost position to Antonelli at the race restart before overtaking him on track, questioned that assessment.

"I don't think it's true. I think if I didn't get Kimi when I overtook him, I don't think I would have won the race," he said. "For once, I would give myself a little bit of credit that I feel like I'm doing a better job than everyone, and I think that can also make a difference. We certainly have a car now capable of beating them … but I think they have a better all-round performing car than what we do."

Zandvoort and Budapest's Hungaroring before it played to McLaren's strengths, but some upcoming circuits may be less favourable.

Mercedes remain well ahead of both Ferrari and McLaren in the constructors' championship and scored more points than any other team over the weekend, 46 to McLaren's 43 and Ferrari's 31.

Norris acknowledged the limitations of his car despite his recent form. "We have a strong car in certain areas. It's not like last year where we were pretty good everywhere," he said. "We're very, very strong in high speed, and that's the place we've improved the car the most, is high-speed performance. No one matches us in high speed, and that's a good thing. But the advantage that they [Mercedes] have to us in slow speed is also crazy. And therefore, I don't have the confidence to say 'yeah, I can easily fight for a championship for the rest of the season'."

"I know I've just won two races in a row and had two poles in a row, but at the minute I don't have the car I need to fight for a championship," added Norris, who sits 83 points behind Antonelli with 11 rounds remaining.

Mercedes team principal Toto Wolff said cost cap restrictions were limiting the pace at which the team could introduce developments.

"We are trying to evenly split that through the season based on our calculations of when we can bring the biggest updates and optimising the championship points," he told reporters. "So the ride has been a bit tougher than at the beginning of the year."

McLaren principal Andrea Stella said he expected Mercedes to accelerate their development programme regardless. "I'm sure their car in the wind tunnel is quite a bit faster than the car they have on track," said Stella. "And they will want to now convert some of this potential into upgrades that make it to the real car. I'm just pretty sure that they will have upgrades."

Antonelli, who turns 20 on Tuesday, faces an additional obstacle in his bid to become Formula One's youngest-ever champion. Mercedes plan to replace his power unit at the Italian Grand Prix in two weeks, which will put him over his permitted component allowance for the season and result in a significant grid penalty at his home race.

Wolff defended the timing of the decision. "Our theory, our calculations say that that's the best track to take it. Obviously, our algorithms don't take the nationality into consideration," he said. "We're here to fight for a championship and not the most PR, so that's what we're going to do."

Monza is a high-speed circuit where the Mercedes power unit is expected to perform strongly, and overtaking opportunities are relatively plentiful, giving Antonelli a realistic chance of recovering positions from the back of the grid.

The Italian driver said he had accepted the team's decision. "I think it still will give me a chance to do a great result and bring home good points," he said.

Ferrari are expected to be competitive at their home race in Monza, with upgrades in the pipeline ahead of the event.