Teenager Karen Khachanov caused a major upset at the ATP Kremlin Cup, knocking out third seed Janko Tipsarevic to reach the last eight in Moscow.
The 17-year-old thrilled his home crowd with a sensational 6-4 6-4 victory that saw him slam down 14 aces. He also didn't face a break point against the two-time US Open quarter-finalist.
Next up for Khachanov will be either Ivo Karlovic or Denis Istomin, who came through first round matches in contrasting fashion.
Karlovic eased past Denis Kudla 6-2 6-3 but Istomin needed three sets to eliminate Andrey Kuznetsov, recovering from a disastrous opener to eventually triumph 6-0 2-6 6-1.
Kazakhstani qualifier Andrey Golubev surprised another seed to reach the quarter-finals, dispatching the sixth-ranked Horacio Zeballos 6-3 6-4.
Reigning champion Andreas Seppi sealed his progression with a 6-3 6-2 result against fellow Italian Paolo Lorenzi.
The second seed will now face Edouard Roger-Vasselin, the Frenchman ousted Sergiy Stakhovsky 7-5 7-5, for a place in this year's semi-finals.
Meanwhile, eighth-seeded Frenchman Adrian Mannarino made an early exit, losing his opening match 3-6 6-4 6-4 to Teymuraz Gabashvili of Russian