Stan Wawrinka defeated Damir Dzumhur 6–3, 6–4 in the quarter-final of the ATP 250 St Petersburg tournament on hard court on 21 September 2018. As the pre-match favourite, Wawrinka delivered a composed performance to advance, breaking down his opponent's resistance across both sets with controlled tennis. The Swiss player's victory extended his run in the tournament and underscored his continued competitiveness at 250-level events during this phase of his career.