Econet said in a statement late on Thursday the court had set June 9 to hear an application for an injunction against Celtel's acquisition of a 65% stake in the Nigerian company.
Econet, which owns 5% of Vmobile, wants to block the deal so it can buy Vmobile under a shareholders agreement that gives it pre-emptive rights over the company.
It says Vmobile breached the agreement by selling the stake to Celtel.
Vmobile said this week it had met all legal and contractual requirements to press ahead with the Celtel deal.
Celtel said on Thursday it was unfazed by the legal challenge - even though Econet spent three years in a court battle to block a similar deal with South Africa's Vodacom - and said the deal had already been completed.
It said a London court had already thrown out Econet's challenge and expected the Nigerian judge to do the same.
Like other operators, Celtel - owned by Kuwait's fast-expanding MTC - has been vying for a foothold in Africa's most populous nation, where pent up demand for communications promises major growth for canny investors.