June 23 (Reuters) - Defending champion Roger Federer extended his unbeaten run on grass to 20 matches by defeating American qualifier Denis Kudla 7-6(1) 7-5 in the Halle Open semi-finals on Saturday.
The pair exchanged early breaks in overcast conditions before top-seeded Federer stamped his authority by winning the tiebreak 7-1, ending Kudla’s 10-set winning streak this week.
Playing his eighth match in less than two weeks, the 36-year-old Federer seemed clearly fatigued but showed great mental strength to save five break points in the second set.
A lapse of concentration from Kudla in the 10th game allowed Federer to grab the only break point on offer before the Swiss served out the match in just under an hour and a half.
Nine-time Halle champion Federer has reached his 12th final on German grass, and will next face either Roberto Bautista Agut of Spain or Croatian Borna Coric.
Federer has won all his seven previous matches against Bautista Agut and holds a 2-0 head-to-head advantage over Coric. (Reporting by Hardik Vyas in Bengaluru Editing by Christian Radnedge)