Dev made his Test cricket debut in Faisalabad, Pakistan on 16 October 1978. Although his match figures were unimpressive, the numbers did not convey any measure of his contribution. He startled the Pakistani batsmen with his pace and bouncers that struck their helmets on more than one occasion. Dev captured his maiden wicket of Sadiq Mohammad with his trademark outswinger. He showcased his all-rounder talent when he scored India's fastest Test half-century off 33 balls and 2 sixes in each of the innings during the 3rd Test match at National Stadium, Karachi, although India lost the match and the series 2–0. In the ensuing series against a visiting West Indies team, he scored his maiden Test century (126) at Feroz Shah Kotla, Delhi in just 124 balls and had a steady bowling performance (17 wickets at 33.00). Ominous signs of Dev's liking for England showed up in the ensuring series, his first outside the sub-continent. He picked up his first 5-wicket haul and all of England's wickets, although it came at a huge cost (48 overs and 146 runs conceded) as England scored a mammoth 633 and won the match comfortably. Dev finished the series with 16 wickets though his batting haul of 45 runs (Average: 7.5) was unimpressive. His debut in ODI Cricket happened in the earlier tour of Pakistan where his individual performance was ordinary and it stayed the same as both Dev and India had a poor campaign at the 1979 Cricket World Cup.