Pedro de la Rosa is set to replace Nick Heidfeld as Pirelli's permanent tyre development tester.
It is expected that German Heidfeld, who left his role as Mercedes' reserve driver in order to take up the Pirelli job, is now set to immediately replace de la Rosa in the Sauber race seat.
Heidfeld, 33, has already done two Pirelli tyre tests, and Auto Motor und Sport reports that his last outing in the role will be this week in Spain.
Testing veteran de la Rosa is an ideal replacement, with seven years of recent experience as McLaren's main and highly respected third driver.
Germany's Auto Motor und Sport claims there were moves to replace de la Rosa with Heidfeld as long ago as Silverstone, but Sauber gave the Spaniard a stay of execution because of a good performance at Valencia.
"Peter Sauber will not be commenting about drivers," a spokesman for the Hinwil based team said on Monday.