Max Verstappen's father, Jos Verstappen, believes Red Bull's 2020 season could be write-off if they don't start closing the gap to Mercedes and Ferrari before the end of the year.
Verstappen claims Red Bull has made little to no progress after the summer break, unlike Ferrari which has made a massive step forward, and is therefore further away than it anticipated it would be.
"We should have been closer, but that is more difficult than we thought," he told Ziggo Sport's Peptalk after the Russian Grand Prix.
"It's very frustrating. In the last races before the summer break it went really well, but after the summer break we did not progress while the other teams have.
"Max cannot change that, we depend on the team, the car is a bit behind, the engine is a bit behind, more work has to be done on this combination if we want to challenge for the title next year."
Verstappen has no doubt his son is capable of fighting for the title if given the right equipment, but is concerned that next season will be another year of struggling as Mercedes and Ferrari continue to find gains that Red Bull haven't.
"We are very concerned there won't be any improvement in the short term," he added. "We depend on the equipment we get and at the moment it is not good enough.
"Put him [Max] in a good car and he will challenge for the world championship, but it still does not look that we will be able to challenge next year.
"The expectation was to close the gap to the competition, but at the moment it does not look like it. We have to work hard to close the gap, otherwise next year will be lost too."
