Red Bull has lost two more of its senior technical staff with Mercedes signing key figures Mark Ellis and Giles Wood.
Both men are set to join the Mercedes Formula 1 team in June 2014 once their current contracts have finished.
Ellis is head of Red Bull's vehicle dynamics, while Wood is its chief engineer for simulation.
They will become Mercedes' performance director and chief engineer for simulation and development respectively.
Wood and Ellis are the first key signings that new Mercedes team bosses Toto Wolff and Paddy Lowe have confirmed since taking over responsibility from Ross Brawn.
The pair are determined to ramp up the momentum that the team has gathered over the past 12 months.
Red Bull's run of success in F1 has been assisted by stability on the engineering front, which has helped its technical chief Adrian Newey produce dominant machinery.
But that stability looks set to end with many of his key allies deciding to move on.
Just months after it emerged that chief aerodynamicist Peter Prodromou has agreed to join McLaren for 2015, Ellis and Wood's departure will come as another blow to Red Bull as it chases its fifth consecutive world championship.