John Isner, Marin Cilic get quarterfinal wins at Delray Beach

''I've played him a couple times before (on the World Tour) and it's a battle each time,'' Anderson said of Matosevic, who has yet to beat the former

John Isner was stretched to three sets for his third consecutive match, beating American qualifier Rhyne Williams 4-6, 6-3, 6-2 :: Robert Prezioso/Getty Images

''I've played him a couple times before (on the World Tour) and it's a battle each time,'' Anderson said of Matosevic, who has yet to beat the former University of Illinois standout in three ATP matches. ''I just hung in there and finally got that breakthrough in the second set.''