Marcelo Rios is the only player on the ATP Tour to become No. 1 without winning a Grand Slam .
Marcelo Rios : No. 1 for six weeks , the first to do so from Chile .
Marcelo Rios is the only Marcelo Rios on the ATP Tour to become No. 1 without winning a Grand Slam .
Marcelo Rios : No. 1 for six weeks , the first to do so from Chile .