(Reuters) - Apple Inc on Monday began its formal defense in an antitrust trial brought by "Fortnite" online game creator Epic Games, by calling its App Store chief Phil Schiller to the stand.

Schiller, who has spent three decades at the iPhone maker, is expected to spend more than 10 hours on the witness stand in federal court in Oakland, California, rebutting Epic's allegations that Apple has monopoly over mobile developers that it abuses by requiring them to use its in-app payments system and pay commissions.