Max Verstappen of Red Bull drives ahead of Lewis Hamilton of Mercedes during the F1 Grand Prix of Spain on May 9 in Barcelona. Photo: VCG

 
Lewis Hamilton faces an uphill battle to keep his title defense alive and to slow Max Verstappen's momentum this weekend when the Formula One circus reassembles at the Red Bull Ring for Sunday's Austrian Grand Prix.

Just five days after the Styrian event in which the Dutchman drove to a commanding lights-to-flag triumph at the same scenic circuit - finishing more than 35 seconds clear of Mercedes' seven-time champion - Verstappen is hoping for a repeat.

Another win would be Verstappen's fifth of the season and extend his 18-point lead on the 36-year-old Briton, who has gone four outings without a victory and called on his team to rekindle the form that earned them the last seven constructors championship titles.

"I don't accept anything," said Hamilton in response to suggestions that Mercedes' decision to develop next year's car at the expense of the current one will condemn him to a performance deficit for the rest of this season. "I think we've still got many races ahead of us and we've got to keep pushing. We're world champions... and we can definitely improve if we put our minds to it.

"If we're not going to develop and improve our car for the rest of the year, this is the result you're going to see, because, as I said, they've really eked out performance in the last few races.

"I'm not going to question the team's logic and how they go through their process, [but] give us an upgrade. We would love an upgrade, but I don't think it's in the pipeline at the moment."

Mercedes team chief Toto Wolff made clear no major upgrades were planned this year following last week's race in which Hamilton and teammate Valtteri Bottas finished second and third behind Verstappen.

But technical boss James Allison revealed on the F1 Nation podcast that the team would be upgrading their W12 car.

"What Toto points out is that next year's rules are a big and hairy affair and demand a huge amount of attention," said Allison. "So, most of the focus of our factory has switched over, but that doesn't mean that there aren't things still in the food chain from prior to that focus switch."

He said Mercedes "have a reasonable number of things that are going to make our car faster in the coming races."