The McLaren and Red Bull Formula 1 teams are in a legal dispute over the latter's new head of aerodynamics Dan Fallows.
Red Bull announced on Wednesday morning that Fallows would become its new aero chief, and that Peter Prodromou, who has agreed a deal to join McLaren, would begin a period of "gardening leave" before taking up his new post at the Woking team.
Fallows was formerly a team leader in Red Bull's aerodynamics division.
He left the squad for a period last year before the announcement that he would return in the lead role.
But prior to that, Fallows had also been tipped for a move to McLaren - with the team mentioning him alongside Prodromou and ex-Lotus men Ettore Griffini and Ciaron Pilbeam when it highlighted a list of new technical recruits its its pre-season launch media material.
A spokesman for McLaren told AUTOSPORT that the team believed it had secured Fallows' services and had referred the situation to its legal team.
"Dan Fallows has a legally binding contract with McLaren, and the matter is now in the hands of our lawyers," said the spokesman.
McLaren has undertaken a number of staff changes in recent months as it bids to recover from a disappointing 2013 season.
Long-time team boss Ron Dennis has reclaimed direct control of the F1 operation and ex-Lotus chief Eric Boullier has come in as racing director, with erstwhile team principal Martin Whitmarsh losing his position.
Neither McLaren nor Red Bull has won a grand prix so far in a 2014 season dominated by Mercedes to date.