Question: The 2010–11 Tour de Ski was the 5th edition of the Tour de Ski and took place from 31 December 2010 to which date, Swiss cross-country skier, Dario Cologna won the Men's class?
Facts:
2010–11 Tour de Ski took place from 31 December 2010 to 9 January 2011
Swiss Dario Cologna won the Men's class
Dario Cologna is a Swiss cross-country skier
Answer: 9 January 2011