Mark Webber has conceded he holds concerns as to whether former team Red Bull has given Max Verstappen a car capable of championship success.
Verstappen finished 14.5 seconds behind Turkish Grand Prix winner Valtteri Bottas but retook the points lead with Lewis Hamilton only fifth at Istanbul Park.
Hamilton was only behind due to a 10-place grid penalty received for an engine change and had set the fastest time in qualifying, further proving Mercedes' superiority across the weekend.
Red Bull has not achieved championship success since Webber left at the end of 2013, a year that saw the team register the last of its four consecutive championship doubles.
“Valtteri drove a great grand prix off the front," Webber told the F1 Nation podcast.
"I think that my little concerns off the back of all that are have Red Bull, are they giving Max the car for closing this championship out?
"I would have lost a lot of money for Valtteri to have the measure of Max in those conditions.
"I thought Verstappen would run rings around him all day long but he couldn’t react to the speed of Valtteri.
"So it was interesting just in terms of performance, dry and wet, and I think Red Bull know they need to react to the Merc pace now."
Red Bull team principal Christian Horner confirmed after the race that Red Bull had sought clarifications from the FIA on an intercooler trick it believes Mercedes is using to extract extra horsepower from its power units.
With six races remaining, Webber stated: “I think right now you would have to think that the Merc has the advantage.
"I just think that the tracks we have just been to…don’t forget that Valtteri stormed to pole in Monza but had the penalty so he could have done what he did in Turkey as well and disappeared at that race without the penalty.
"So I think they are just starting to get a bit more of a spring in their step at this crucial point in the championship."