Nick Kyrgios will face Luxembourg’s Gilles Muller in the Japan Open quarter-finals after the Australian was gifted a run into the final eight.
The tournament’s sixth seed, Kyrgios moved through to the quarter-finals without hitting a ball when his opponent Czech veteran Radek Stepanek withdrew with a back injury.
World No.106 Stepanek, who turns 38 next month, failed to take to the court.
He has been acting as a part-time mentor for 21-year-old Kyrgios, who has risen to 15th in the world rankings.
Kyrgios has won two titles this season, in Marseille and Atlanta, but faces an in form player in Muller, the world No.36 who is just two spots shy of his highest ranking.
The 33-year-old overcame Cypriot Marcos Baghdatis 6-3 6-4 in their second round clash.
Marin Cilic, David Goffin, Juan Monaco and Joao Sousa have advanced to the quarters, with top seed Kei Nishikori also pulling out with a back injury midway through his match with Sousa.