Porsche LMP1 candidate Brendon Hartley tested the German manufacturer's 2014 World Endurance Championship challenger for the first time this week.
The former Red Bull junior racer drove the petrol-electric hybrid over the course of a three-day test at Monza, sharing the car with Porsche stalwarts Timo Bernhard and Romain Dumas.
Long-time Porsche driver Marc Lieb, who is in line for the second vacant seat, was not present at the test, and is likely to drive the Porsche coupe at Paul Ricard later this month.
A Porsche spokesman explained that the team did not want to have both potential drivers at the same test to "avoid competition between them".
No further details of the Monza test have been revealed.
Porsche is aiming to announce the remaining two drivers alongside Bernhard, Dumas, Neel Jani and Mark Webber before the end of the year. One potential date is the manufacturer's annual prize-giving event on December 14.