Further strong performances during the Shield season saw him selected at age 19 for the 1961 Ashes tour under Richie Benaud. Following an injury to Benaud, Australia replaced him with a third seamer, allowing McKenzie to make his debut in the Second Test at Lord's during the "Battle of the Ridge". In his first innings, he made 34 on his twentieth birthday batting at number 10 on a difficult pitch. The last two wickets added 102 and Australia gained a lead of 134. In England's second innings, McKenzie captured the prized wickets of Ted Dexter and Peter May, and took the last three wickets in twelve balls to give 5/37 on debut. Australia went on to win by five wickets. After losing the Third Test at Headingley, Australia won the fourth Test at Old Trafford with McKenzie again making a valuable contribution with the bat. With a lead of only 177 with nine wickets down in the second innings, McKenzie joined Alan Davidson. He held his end for 32 runs while Davidson's powerful hitting saw 98 added for Australia's highest tenth wicket partnership on English soil. This allowed Benaud to bowl Australia to victory on the final day. The youngest member of the touring party, McKenzie was one of eight bowlers to take at least fifty wickets.