Does Nicolas Mahut or Elena Bovina have the highest career singles world ranking?
Nicolas Mahut:  In singles, he reached a career-high Association of Tennis Professionals (ATP) ranking of world No. 37 on 5 May 2014. Elena Bovina: Elena Olegovna Bovina (Елена Олеговна Бовина ) (born 10 March 1983) is a professional tennis player from Russia. Elena Bovina:  She reached her career-high singles ranking of World No. 14 in April 2005.
Elena Olegovna Bovina