Russell posted a 6-3, 6-1 victory, his first in three career meetings with Fish. Their other two confrontations had come in 2010, one of those matches being played on grass and the other on clay.
Second-seeded John Isner also advanced, but had a struggle on his hands before defeating Horacio Zeballos 6-7 (3-7), 6-4, 6-2. Isner will take on Ryan Sweeting in the quarterfinals after Sweeting downed Bobby Reynolds 6-3, 6-2.
In other second-round matchups Thursday, Ryan Harrison defeated Igor Kunitsyn 6-2, 6-4, Juan Monaco was a 6-3, 6-3 winner over Tatsuma Ito and Kevin Anderson knocked off Sam Querrey 7-6 (7-3), 3-6, 7-6 (7-2).
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