LMP2 star Paul-Loup Chatin will drive Audi's LMP1 machinery in FIA WEC's post-season test in Bahrain, standing in for original pick Antonio Giovinazzi.
The Italian, who is leading the GP2 standings with one round to go as a series newcomer, was selected to drive for Audi in the LMP1 rookie test.
However, the date of the test clashes with his commitments in the F1 feeder series and he is unable to take part as a result.
He will be replaced Paul-Loup Chatin, who was the ELMS champion in the LMPC class in 2013 and then in the LMP2 category a year later.
After finishing fourth with Signatech in WEC's LMP2 class last year, he returned to the European series with Panis-Barthez Competition for 2016 - but has also since made a WEC comeback with the DC Racing team.
Gustavo Menezes and Pipo Derani are still set for their tests with Porsche and Toyota respectively with both teams bringing two cars.
In addition, ex-Formula 1 driver and four-time Le Mans winner Yannick Dalmas, the championship's FIA Driver Adviser, will test with all three teams.
LMP1 privateer team ByKolles and five LMP2 teams plan to take part in the test.
G-Drive Racing picked Indy Lights race winner Felix Serralles and 20-year-old Briton Tom Jackson, who was third in BRDC F4 last year and raced in ELMS in 2016, as its drivers.
The other team to reveal names was RGR Sport by Morand, which is set to test Pro Mazda drivers Pato O'Ward and Will Owen.
Ferrari and Aston Martin will represent the LMGTE category with one and two cars each, the latter selecting GP2 driver and recent WEC debutant Alex Lynn.
Aston Martin will also field four other British drivers - Manor F1 hopeful Jordan King, GP3 regular and former Caterham F1 protege Matt Parry, and GT racing notables Ross Gunn and Euan Hankey.
Turkish driver Salih Yoluc, runner-up in the Michelin GT3 Le Mans Cup this year, will also drive in the test.