Australian John Millman has been beaten by Ryan Harrison in a hard-fought three-set second round match at the Atlanta Open on Thursday.
Millman, ranked 174, won a first-set tie-breaker but fourth-seeded American prevailed 6-7 (2-7) 7-6 (7-4) 7-5.
The encounter lasted two hours and 45 minutes, with the decisive break of Millman's serve coming in the 11th game of the final set.
Top-seeded Jack Sock made light work of Israel's Dudi Sela, winning 6-4 6-3.
The American setting up a quarter-final showdown against fifth-seeded Kyle Edmund after the Briton recorded a come-from-behind victory over German Peter Gojowczyk.
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Edmund lost the the first set but recovered to come out on top 2-6 6-4 7-5 in the rain-interrupted match.
Christopher Eubanks, a 6-4 4-6 6-2 winner over eighth-seeded Jared Donaldson, will play Harrison in an all-American last-eight clash.
In the other quarter-finals, second-seeded John Isner will play Slovakia's Lukas Lacko and third-seeded Gilles Muller of Luxembourg will face American Tommy Paul.
