His next tournament was at Delray Beach where he caused an upset over World number 20 and second seed John Isner in the first round .
Matosevic then played in Memphis but lost in the first round .
Matosevic 's next tournament was at Delray Beach where he caused an upset over World number 20 and second seed John Isner in the round round .
Matosevic then played in Memphis but lost in the first round .