John Millman upset Hubert Hurkacz 5–7, 7–6, 6–3 in the first round of the Madrid Masters on clay on 4 May 2021. Millman, ranked well below Hurkacz in the pre-match odds at 2.98 against his opponent's 1.45, recovered from losing the opening set to force a tiebreak in the second. The Australian won the crucial second-set tiebreak and then dominated the third set to secure a significant upset victory. This result marked a notable upset at a Masters 1000 event, where Hurkacz had entered as the clear favourite but failed to convert that advantage on the Madrid clay court.