Charles Leclerc and Alfonso Celis Jr will be running in Mexico City this week with Sauber and Force India respectively as the teams conduct 2018 tyre testing for Pirelli.
The Italian manufacturer and exclusive supplier to F1 is allowed 29 days of testing in the year as part of its development program for next season.
Ferrari-backed Leclerc , a contender for a drive with Sauber in 2018, is scheduled to be behind the wheel of the Swiss team's C36 on both days of the test.
Alfonso Celis, who ran with Force India in last Friday's first free practice, will run with the VJM10 on Tuesday.
Pirelli's program is a blind test for drivers, meaning they do not know which compounds they are testing or when. Pirelli collects the data which is then shared with all teams openly.