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: Even the Swedes in tennis, usually as prone to over-excitement as an IKEA wardrobe, are getting excited about this one. Andy Murray's coach Jonas Bjorkman hailed Friday's Wimbledon semi-final as a match between 'these giants of the game' while his opposite number in Roger Federer's corner, Stefan Edberg, was looking rather more intense than is normal. Ex-world No 1 Mats Wilander declared: 'This is the most excited I have been for a match between the two of them ever in terms of their rivalry. 'Does Roger believe he can win a Grand Slam at this moment? 'I think it will go the distance. Both of them will figure out a way to prolong the match to the very end.'Andy Murray's coach says Friday's match is between 'giants of the game'Murray and Federer face off for a place in the 2015 Wimbledon finalThe pair have a cordial truce but still get under each other's skin regularlyJonas Bjorkman says Murray needs the support of the crowd on FridayWimbledon results: CLICK HERE for all the latest from day eleven 
 Question:One concern for those hoping for a Murray triumph on Sunday is that, since returning from back surgery at the beginning of last year, he has not beaten either _ or Djokovic.

Roger Federer