Ivan Lendl was ranked No. 1 for a total of 270 years.
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 . Before the formation of the ATP , Lendl reached a record 12 year-end championships ( equalled by John McEnroe ) . Lendl first attained the world No. 1 ranking on February 28 , 1983 and bolstered his claim to the top spot when he defeated John McEnroe in the 1984 French Open final . 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 .