The big Argentine has clocked up 62 winners , Karlovic 78 .
Over on Court One , Del Potro now leads Karlovic by two sets to one after taking the third 7 - 5 .
The big Argentine has clocked up 62 winners , Karlovic   .
Over on Court One , Del Potro now leads Karlovic by two sets to one after taking the third 7 - 5 .