Honda's latest Formula 1 upgrade has moved it ahead of Renault in the engine pecking order, according to Toro Rosso team boss Franz Tost.
The Japanese manufacturer introduced its second upgrade of the season in Russia on Friday, and although it has reverted to an older specification for the rest of the weekend that update has been hailed as a significant step forward.
"Honda is making big steps forward," Tost told Autosport.
"Yesterday we had the new spec in the car and it was really fantastic."
Asked if he felt Honda had caught Renault with its upgrade, Tost said: "It is in front of Renault. [The] complete package.
"We had it in the car yesterday, but we have to start from the back of the grid and then we decided we go back to spec 2 just to save some milage and to make some fine tuning.
"In Suzuka we will have it."
Honda's latest upgrade is another significant internal combustion engine upgrade married to minor updates to the other components for optimisation.
Tost said Honda will not keep the same design for next year although he would only confirm "there are changes, but I do not want to go into details - I can only tell you they are really on a good way".
Red Bull driver Max Verstappen has talked up Honda several times since his team confirmed it would use Honda engines next season.
He said he agreed that Honda's upgrade moved it ahead of Renault when asked by Autosport/Motorsport.com about Tost's assessment.
Verstappen, who said earlier this week that Honda will start next season at least level with Renault, added: "As soon as everything was confirmed, that we were going to run with Honda next year, for sure you pay a lot of attention to it.
"You could see definitely the steps they were making and this weekend was a very positive one."