Answer
Khachanov reached the semi-finals of the US Open in 2017 and the Australian Open in 2018. In the US Open, he defeated the No. 3 seed Alexander Zverev in the round of 16, before losing to Rafael Nadal in the semi-finals. In the Australian Open, he defeated the No. 2 seed Roger Federer in the quarterfinals, before losing to Novak Djokovic in the semi-finals.