Red Bull's head of aerodynamics Peter Prodromou has agreed to return to McLaren having worked at the Woking-based marque from 1991-2006.
It is understood Prodromou was in line to succeed Adrian Newey at Red Bull whenever the team's chief technical officer decided to step down.
Prodromou has been a key player in Red Bull's dominance over the past few years, with the team on the brink of winning a fourth consecutive drivers' crown with Sebastian Vettel in Japan this weekend.
But with Prodromou's Red Bull contract not expiring until the end of next year, and with team principal Christian Horner seemingly ready to hold him to it, the two teams appear poised for a battle.
McLaren managing director Jonathan Neale said: "We have to remember the contract Peter has at the moment is with Red Bull, and I have to respect that.
"It is for them to talk about what his terms are and what his leave dates are, but in terms of our position, yes we have recruited Peter, and we are really excited about him joining the team.
"It is not a one-off thing we are doing as we have made some moves during the course of this year. There are some other things we are doing to strengthen our team.
"So it is a series of moves as we head towards 2015 with Honda to make sure this team stays at the forefront of F1 and is set for winning ways."
Horner, however, has warned McLaren if Prodromou is intent on leaving it will be later rather than sooner.
"The contents of any contract will be confidential between the company and the individual," said Horner.
"We've enjoyed a long relationship with Peter, he's a valuable member of the team, and there's quite a duration left on his contract.
"We won't force him to stay. If it's his choice to leave then he'll leave at the end of his contract, but we are quite some way off that."
From Jenson Button's perspective, with the team poised to complete a full season without a podium for only the third time in their history - 1971 and 1980 the others - he can at least see moves are being made to ensure this year goes down as a very rare occurrence.
"Looking at this season it has not been a great year for us, it has been a pretty tough one for us all," said Button.
"You do have to remember we have brought very good cars in the last few years, have got many victories and been close to winning many world championships.
"The people working inside this team, and have been for many years, are still doing a mega job, but it is great we are adding to their skills and experience.
"It is great that Jonathan, Martin (Whitmarsh, team principal) and everyone else are looking outside the box, which is going to help us more in the future."