Conversation so far:
Can you provide me with information on World No.
! and Grand Slam history?
Safin held the No.
1 ATP ranking for 9 weeks during 2000 .
Are there any other interesting aspects about this article?
he won his first Grand Slam tournament at the US Open, becoming the only Russian in history to win this tournament in the men's singles draw.
Did he celebrate after he won the tournament?
CANNOTANSWER.
What happened after he won the tournament?
He barely missed finishing the year as #1, the top spot being overtaken by Gustavo Kuerten at the last match of the season.

Question: What important happened after that?
Self-contained rewrite: What important happened to Marat Safin after being overtaken by Gustavo Kuerten?