The Uzbek pair of Istomin and Inoyatov beat the Indo-Taipei 3-6, 6-1, 10-5 in a well-contested semi-final.
Indian Davis Cupper Bopanna and Lu had to be content with 40 ATP points and $2700 for their effort.
Local hero and second seeded Istomin joined fourth seeded Christophe Rochus of Belgium, eighth seeded Sergiy Stakhovsky (Ukr) and unseeded Lukas Lacko of Slovakia in the quarter-finals of the men's singles.
Unseeded Slovakian Lucas Lacko stopped the run of Uzbek lucky looser Arsen Asanov 6-0, 6-1, while fourth seeded Belgian Christophe Rochus scored a 7-6 (3), 6-3 win over qualifier Andrei Gorban of Moldova.
Ukrainian eighth seed Sergiy Stakhovsky outplayed Russian qualifier Konstantin Kravchuk 6-1, 6-4, while second seeded Uzbek Denis Istomin fought off high fever and Kazakhstan's Yuri Schukin to win 3-6, 6-1, 6-3 and make the eight.
In Friday's quarter-finals, Oleksandr Dolgopolov Jr. will take on Alexandre Kudryavtsev, while Marcos Baghdatis will take on Andrey Kumantsov in the top half.
In the bottom half, Istomin meets Stakhovsky, while Lukas Lacko takes on Christophe Rochus.
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