Mercedes boss Toto Wolff says the development of its 2020 car was stopped "a long time ago" to allow the team to focus its attention on next year's program.
Mercedes is in the midst of another dominant season, with the Brackley squad winning nine of the eleven races held so far this year and enjoying a 100 per cent success rate in qualifying.
A prevailing strategy and the skills of Max Verstappen thwarted Mercedes efforts at Silverstone's second race while circumstances granted a shock win to AlphaTauri's Pierre Gasly at Monza.
Mercedes is inching closer to a seventh consecutive Constructors' title, but Red Bull is slowly creeping up on its arch-rival.
A fact that hasn't surprised Wolff who expects the Milton Keyes-based outfit and its star driver to challenge his team more closely the final part of the 2020 season.
However, according to the Austrian, Red Bull's closing of the gap likely reflects a development disparity between the two teams, with the former sustaining an update push while the latter has already switched most of its resources to 2021.
"We finished them a long time ago," Wolff said at the Nürburgring, referring to the team's upgrades.
"That has always been in the past what we looked at. It’s a very thoroughly thought-through decision, because not in every championship can you afford to close the book early.
"But the rules change quite a lot for next year. And in that respect, we decided to, like in the previous years, to switch to next year’s car and this is why you can see that shifting performance between the teams.
"I think we always having a very strong start and middle of the season and then whoever continues to develop is strong at the end."
Mercedes trackside engineer Andrew Shovlin believes the closer competition from Red Bull reflects the latter's historical pattern in terms of in-season development.
"I think they are developing quicker than we are at the moment," Shovlin explained.
"And we've seen that progressively. But to be honest, we've seen that in most of the recent years, they tend not to start as strongly as we do.
"I can't really think of a year recently where they've not been with us by the end.
"So if we see that trend continue, then the remaining races are going to get tougher, and it will be harder to try and keep getting the pole on Saturday and winning on a Sunday."
Gallery: The beautiful wives and girlfriends of F1 drivers
Keep up to date with all the F1 news via Facebook and Twitter
