Conversation so far:
What happened in 2011?
Entering the 2011 season, Kaymer turned down a chance to become a full PGA Tour member.
What did he do instead?
He stated he would concentrate on the European Tour for 2011, but would play several U.S.
events as well.
Which tournaments did he play in Europe?
WGC-Accenture Match Play Championship.
Which tournaments did he win in 2011?
In January, Kaymer claimed his third Abu Dhabi HSBC Golf Championship title.
Did he have any problems in 2011?
CANNOTANSWER.

Question: How did he become the number one ranked palyer?
Self-contained rewrite: How did Kaymer become the number one ranked palyer?