Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: (CNN) -- After Venus Williams beat Caroline Wozniacki at the Dubai Duty Free Tennis Championships, it looked as if a first all Williams tennis final in five years was on the cards. But someone forgot to tell Alize Cornet. The Frenchwoman stunned a sluggish Serena Williams in the second semifinal Friday, meaning a Williams versus Williams clash for silverware -- they haven't met in a finale since the year-end championships in 2009 -- will have to wait. It was Serena Williams' first tournament since a back injury hampered the 17-time grand slam champion at the Australian Open, and she accepted a wildcard from organizers to fend off the boredom from just practicing.Alize Cornet beats world No. 1 Serena Williams in straight sets in DubaiThe French No. 1 had lost all three of her previous matches against WilliamsWilliams was playing her first tournament since suffering a back injuryCornet prevents an all Williams final after Venus Williams earlier won her semifinal 
 Question:"I forgot it was _ on the other side and just got on with my game."

Serena Williams