The Wallabies endured a shocking run in 2018; in June, Cheika led the team to a series defeat against Ireland, losing 2–1 having won the first test 18–9. However, a first loss to Ireland at home since 1979 in the second test (26–21) followed by a close encounter in the third test (16–20), meant Ireland claimed a first ever series win over Australia. Despite losing the series, the Wallabies out scored their opposition in terms of tries, scoring 6 tries to 3. It was also a first for Cheika in the second test, naming an unchanged matchday 23 for two consecutive tests, retaining the same team from the first test.