Conversation so far:
Where did Martin Kaymer play in 2014?
In 2014 Martin Kaymer played in The Players Championship in Florida, the US Open at Pinehearst North Carolina, and the PGA Grand Slam in Bermuda.
Did Martin Kaymer win any tournaments in 2014?
Martin Kaymer won the Players Championship, the US Open, and the PGA Grand Slam.
What was Martin Kaymer's score for his 2014 tournaments?
Who else was playing in the 2014 tournaments with Martin Kaymer?
Other players who played with Martin Kaymer include Bubba Watson, Rory McIlroy, and Jim Furyk.

Question: when did he win the U.S. Open?
Self-contained rewrite: When did Martin Kaymer win the U.S. Open?