Complex sentence: Thanasi Kokkinakis (Greek: Θανάσης Κοκκινάκης; born 10 April 1996) is an Australian tennis player of Greek origin who filled-in on the United States and German teams during the 2013 Hopman Cup as a replacement for injured John Isner and Tommy Haas.
Split into simpler sentences: Thanasi Kokkinakis (Greek: Θανάσης Κοκκινάκης; born 10 April 1996) is an Australian tennis player of Greek heritage. He also filled-in on the United States and German teams during the 2013 Hopman Cup as a replacement for injured John Isner and Tommy Haas.