Mariner's third England cap came in the return World Cup qualifier in Luxembourg, scoring a last-minute goal in a 2–0 win which England really needed to win by much more in order to give themselves half a chance of qualifying for the 1978 World Cup in Argentina. By now, Mariner had become one of a number of 'target man'-type centre forwards for England coach Ron Greenwood to select from, with Stuart Pearson and Bob Latchford also on the scene. It was Mariner, however, who would be selected the majority of the time.