Donald Young has upset No. 2 seed John Isner 7-6 3-6 7-6 in the quarter-finals at the Memphis Open for his first victory in four tries over the world's 23rd-ranked player.
American Young reached his seventh career semi-final and second in Memphis by overcoming his big-serving compatriot in the tiebreakers of a match that took two hours 23 minutes.
"With him, it comes down to a couple points here and there, and I was able to get those today and I was able to hold my serve for the most part of the match and just defend well," Young said.
"I'm happy to get through it. I don't know how it happened. I just stayed focused and battled."
Young will play fellow American Ryan Harrison on Saturday, after Harrison beat Damir Dzumhur of Bosnia-Herzegovina 6-3 6-4 in the late match.
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Isner was the last seeded player left, and Australia's only hope Matthew Ebden went out in the quarters with a 7-6 6-4 loss to Nikoloz Basilashvili of Georgia in an hour and 44 minutes.
"He's beaten me every other time we've played so I wanted to get at least one," Young said.
"I'm just happy I was able to stay focused, come through, deal with a little tightness and still prevail. So I'm happy with the performance."
