Question: Which of the following was the greatest service returner in the history of the game of tennis: Andre Agassi or Martina Hingis?
Sentence (from "Martina Hingis"): Martina Hingis (born 30 September 1980) is a Swiss professional tennis player, a former world No. 1 singles player and currently ranked world No. 2 in doubles by the WTA.
Relevant evidence: Yes