Ivan Lendl was listed No. 1 for a total of 270 weeks.
Ivan Lendl ( [ ˈɪvan ˈlɛndl̩ ] ; born March 7 , 1960 ) is a former world No. 1 professional tennis player and is currently coaching current world No. 1 Andy Murray , alongside Jamie Delgado . He finished four years ranked as the world 's top player ( 1985 -- 1987 and 1989 ) and was ranked No. 1 for a total of 270 weeks and set a new record previously held by Jimmy Connors , since broken by Pete Sampras and Roger Federer .