Pascal Wehrlein is shaping up to make his return to the Sauber cockpit in Bahrain, according to Mercedes chief Toto Wolff.

Currently, German Wehrlein is reportedly recovering his fitness after injuring his back in a race of champions crash in the winter.

In China, Wolff denied raging speculation that the 22-year-old is actually caught up in a political dispute involving Sauber's engine supplier Ferrari.

It was also said in Shanghai that Antonio Giovinazzi - Ferrari's reserve driver who crashed both in qualifying and during the race in China - could race in Wehrlein's place for a third consecutive time in Bahrain this weekend.

"Pascal is training and doing weights, preparing himself as much as possible for Bahrain," Wolff, the head of Mercedes's development programme, told DPA news agency.

"I am only hearing good things about it - that he is feeling better and stronger. At the moment, everything is pointing at him sitting in the car in Bahrain."

Sauber are one of three pointless teams heading into this weekend's race.