"Sahib" departed Malta on 7 December to patrol off Naples, Italy; her orders were changed five days later to patrol the Gulf of Tunis instead. On 14 December, northwest of Cape Bon, Tunsia, "Sahib" sighted the Italian merchant ships "Honestas" and "Castelverde" escorted by two Italian torpedo boats and several aircraft. "Honestas" was carrying 1,000 tons of ammunition and 50 vehicles; "Sahib" fired five torpedoes at it. One struck, and "Honestas" sank. After evading the merchants' escorts, "Sahib" returned to periscope depth and spotted the other merchant, but it was blown up by another Royal Navy submarine, , before "Sahib" could attack it. On 20 December, she attacked and damaged the Italian coastal trading vessel "Ist no.23" with gunfire and torpedoes; the torpedoes however ran under the ship and did not explode. "Ist no.23" was later taken in tow back to harbour. On 25 December, "Sahib" ended her patrol in Algiers, joining the 8th Submarine Flotilla.