Sentence:  Murray started well against Marcos Baghdatis before slumping to defeat in <WSD>straight</WSD> sets and the British No1 admitted he may not have been mentally prepared for the rigours of the ATP Tour after a gruelling start to 2011. 
Meaning of the word marked with <WSD> tags:  Describing the sets in a match of which the winner did not lose a single set. (from 19thc.)