Stan Wawrinka continued his injury comeback with a hard-fought win over Karen Khachanov to reach the quarterfinals of the St. Petersburg Open on Wednesday.
Wawrinka saved two set points in each set on his way to winning 7-6 (10), 7-6 (1) over the fourth-seeded Khachanov, who at No. 24 is ranked 64 places above Wawrinka.
Wawrinka's quarterfinal opponent will be either defending champion Damir Dzumhur or Guido Pella.
Also Wednesday, fifth-seeded Roberto Bautista Agut beat qualifier Luca Vanni 7-5, 6-2 in their first-round match.
Canadian 19-year-old Denis Shapovalov, seeded seventh, won 7-6 (3), 6-2 against qualifier Adrian Menendez-Maceiras. He'll meet Matteo Berrettini of Italy in the second round.