Nishikori retires injured sending Eubanks into Houston Open quarter-finals

American Christopher Eubanks advanced to the last quarter-finals of the Houston Open when Japanese Kei Nishikori, the No 8 seed, retired on Thursday evening at River Oaks Country Club.

Eubanks, ranked No 117, led 6-1 when Nishikori, ranked No 66, pulled out due to injury.

The American will face No 4 seed Brandon Nakashima next.

Ahead of his victory, Christopher Eubanks beat Australian Rinky Hijikata (6-2, 4-6, 6-3).

The 35-year-old Japanese won against American qualifier Mitchell Krueger (6-4, 6-2) in the previous round of the Houston tournament.

Houston ATP 250, other second-round results (River Oaks Country Club, clay, USD 680.140, most recent results first):

• Alex Michelsen vs. Adrian Mannarino
• Adam Walton vs. Frances Tiafoe
• Brandon Nakashima beat Mackenzie McDonald: 6-1, 7-5
• Aleksandar Kovacevic beat Corentin Denolly (Q): 6-3, 6-3
• Tommy Paul (1) beat Cristian Garin (WC): 2-6, 6-2, 7-6 (5)
• Colton Smith (Q) beat Ethan Quinn (WC): 6-3, 6-4
• Jenson Brooksby (Q) beat Alejandro Tabilo (3): 3-6, 6-4, 7-6 (6)