John Millman defeated Aslan Karatsev 6–3, 6–2 in the second round of the ATP 250 St Petersburg tournament on hard court, producing a significant upset against the pre-match favourite. Karatsev, who carried odds of 1.27 to prevail, was outplayed by Millman, who secured the victory despite entering as the 4.26 underdog. The Australian's dominant performance saw him advance to the quarter-finals with a commanding display across both sets. The result represents a notable reversal of expectations and demonstrates Millman's capability to trouble higher-ranked opponents on hard courts.