Don Callahan may be an unfamiliar name to many in India, but for companies in the country’s $150 billion outsourcing business, the head of operations and technology at Citigroup Inc. could be quite the game-changer.

Callahan will decide the winner of the largest outsourcing contract up for grabs in close to a decade. The last time the contract was awarded, in 2008, it was worth $2.5 billion for a 10-year period.In October, industry leader Tata Consultancy Services Ltd (TCS), which won the contract in 2008, and its smaller rivals Infosys Ltd and Wipro Ltd took turns to woo Callahan while he was in India, according to two executives familiar with the matter.

TCS won the $2.5 billion outsourcing work in October 2008 for managing Citigroup’s back office operations for nine-and-a-half years. TCS also paid $505 million to Citigroup to buy its India-based captive business processing outsourcing arm, Citigroup Global Services Ltd. Additionally, Citigroup gives more than $200 million in business annually to TCS, $100 million to Infosys and at least $50 million to Wipro.

Wang expects American MNC IBM to bid for the contract as well as its “blockchain and security teams are rapidly becoming top-tier in the industry”.