Atlanta, GA (Sports Network) - Top seed and two-time finalist John Isner will face former world No. 1 Lleyton Hewitt in the semifinals at the BB&T Atlanta Open.

Isner fired 21 aces while edging fellow American James Blake in a pair of tiebreaks, 7-1 and 7-5. The towering right-hander was a runner-up at this tournament in 2010 and 2011, losing to countryman Mardy Fish both times.

Meanwhile, the seventh-seeded Hewitt fought back from a set down and finished strong in a 1-6, 6-3, 6-0 victory over third-seeded Croat Ivan Dodig in the first quarterfinal on Friday.

The Aussie beat Isner in three sets two weeks ago in the Newport semifinals.

Friday's other two quarterfinals will pit second-seeded South African Kevin Anderson against Uzbekistan's Denis Istomin and American Ryan Harrison against Colombian Santiago Giraldo.