Conversation so far:
Who was Martina Hingis?
Martina Hingis is a Swiss former professional tennis player.
How many career games did Martina Hingis play?
When did Martina Hingis retire?
She retired in November 2007 after being hampered by a hip injury for several months.
Was Martina Hingis injured often?
Martina Hingis had a right ankle surgery in October of 2001, and a left ankle surgery in May of 2002. After that she struggled with injuries.
Did Martina Hingis come back from her 2007 retirement?
In July 2013, Martina Hingis came out of retirement to play the doubles events of the North American hard-court season.

Question: What people did she play against?
Self-contained rewrite: What people did Martina Hingis play against?