Thierry Neuville has warned his Hyundai World Rally Championship team that it has "no chance" of beating Ott Tanak and Toyota in 2019 without a step up in car development.
As the runner-up in the 2018 drivers' standings, Neuville has not restricted his criticism his team's management, as he also lambasted his Hyundai team-mates for a lack of support throughout the year.
"For sure, if we don't grow in speed and performance, we have no chance [against Ott Tanak and Toyota] next year," Neuville told Autosport.
"We need development and now we're going to see; it's a general improvement we need, it's not just one place where we need to make the car faster."
Hyundai's plans for its full 2019 driver line-up remain a mystery, which is expected to be unravelled by the end of next week following an extended end-of-season briefing for the whole team in Seoul.
But Neuville argues that whoever drives alongside him at the team in 2019 needs to secure improved results.
Neuville is the only driver to win for Hyundai since Hayden Paddon's Rally Argentina success early in 2016 - a statistic he feels was highlighted after another season that ended without a title.
"I am on my own a lot of the time," said Neuville. "I think you can see this year - the other teams had good support for their drivers, but I didn't really have this.
"Of course this is going to make it difficult for the [manufacturers'] championship [too]."
Hyundai team principal Michel Nandan accepted the challenge issued by his number one driver.
"I don't know what they [Toyota] have planned for their development," he said.
"But everybody is working on next season and we have to hurry up and catch-up.
"That's all I can say. We have things in work. We had the new engine [in Neuville's car] in Australia - this had a new specification of cylinder head - and we have just to continue and do the same with more work.
"Through the winter, we will be working more on the engine, the transmission and the suspension is something where we are working regularly. This will not stop."
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