Oval was notoriously flat, but McKenzie was an expert on getting batsmen out on dull wickets and used the humid atmosphere and fresh pitch to bowl Bob Barber for a duck and have John Edrich caught by the ever-reliable Simpson at slip. McKenzie took 6/48 to have England out for 241 and Australia won by an innings. He took 3/17 in the second innings in the Fifth Test to finish with 16 wickets (29.18), the chief wicket taker along with Neil Hawke who took 16 wickets (26.18). Thereafter McKenzie became one of the most consistent opening bowlers in the world. He toured South Africa in 1966–67 and in 1967–68 was dropped for the final two Tests after taking his only ten wicket match haul against India. This was speculated to be due to fears that his dominance over the Indian batsmen was diminishing public interest in the series. In 1968, McKenzie became a full-time cricketer, believing that it would offer him the best chance of financial security. At the time the Australian Cricket Board regarded its players as amateurs and paid them accordingly. McKenzie joined Leicestershire, captained until 1968 by the Western Australian skipper and former England Test stalwart Tony Lock. He took over four hundred wickets for the county and was instrumental in its four One Day Cricket trophies in the early 1970s and winning their first County Championship in 1975. In 1968–69 he took 30 wickets (25.26) against the visiting West Indies and at 27 became the youngest man to take 200 Test wickets, a record since beaten. Another 21 wickets (21.00) came on the Indian tour of 1968–69, but when the Australian team proceeded to South Africa his form slumped (1/333 in four Tests) and they were whitewashed. It led to suspicions that he had contracted hepatitis. He played in the first four Tests of the 1970–71 Ashes series against England, taking 4/66 in the Second Test at Perth, the first played at the WACA Ground and 2–22 in the first ever One Day International at Melbourne. In the Fourth Test at Sydney McKenzie retired hurt after being hit in the face by a bouncer from John Snow as the England fast bowler took 7–40 in England's 299 run victory. He recovered sufficiently to break Geoff Boycott's forearm in a tour match just before the vital Seventh Test, but was not recalled and was left stranded on