The Polish driver stunned the sport with his first asphalt outing in the DS3 on last week's Canaries Rally, but his WRC2 debut in Portugal is expected to be more complicated for the former Canadian Grand Prix winner.
Kubica's gravel experience is limited to just 40 miles in one of his own Group N cars and, while he will test his DS3 ahead of the Faro event, Citroen team principal Yves Matton expects him to have questions.
Loeb and current Citroen team leader Mikko Hirvonen will therefore be available to support Kubica.
"When he does his first laps on gravel, he will have a lot of questions," Matton said.
"And Seb and Mikko have done so many kilometres on gravel - and they have different driving styles – so I will not say all the answers will be there, but a lot of answers will be there and he can win a lot of time like this.
"But first he has to do a couple of kilometres just to understand."
Kubica admitted himself that gravel will pose a completely different challenge for him.
"In my life," Kubica said, "I have not done much on gravel and this will be a big challenge and big fun."
In addition to the test, Kubica will contest the Fafe Rallysprint, now a traditional warm-up for the Portuguese WRC round, on April 6.