Via Wikipedia (links and footnotes in the original), I stumbled upon this remarkable anecdote of the time when Mario Vargas Llosa punched Gabriel García Márquez in the face:

“In 1971, Vargas Llosa published García Márquez: Story of a Deicide (García Márquez: historia de un deicidio), which was his doctoral thesis for the Complutense University of Madrid.^[36][37] Although Vargas Llosa wrote this book-length study about his then friend, the Colombian Nobel laureate writer Gabriel García Márquez, they did not speak to each other again. In 1976, Vargas Llosa punched García Márquez in the face at the Palacio de Bellas Artes in Mexico City, ending the friendship.^[38] Neither writer publicly stated the underlying reasons for the quarrel.^[39] A photograph of García Márquez sporting a black eye was published in 2007, reigniting public interest in the feud.^[40] Despite the decades of silence, in 2007, Vargas Llosa agreed to allow part of his book to be used as the introduction to a 40th-anniversary edition of García Márquez’s One Hundred Years of Solitude, which was re-released in Spain and throughout Latin America that year.^[41] Historia de un Deicidio was also reissued in that year, as part of Vargas Llosa’s complete works.”

See also this story about the quarrel in El País as well as footnotes 38 and 39 below the fold.

[36] Jaime Perales Contreras, review of Mario Vargas Llosa, Obras Completas, Vol. VI, Tomo. I, in Americas Magazine, Organization of American States, July–August 2007.

[37] Shaw 1973, p. 431. [Full cite: Shaw, D.L. (1973), “Review of Vargas Llosa, García Márquez: historia de un deicidio“, Modern Language Review, Vol. 68, no. 2: 430-431.]

[38] “Todo occurrió en 1976, en el Palacio de Bellas Artes de la ciudad de México. … todos los presentes quedaron impresionados y sorprendidos por el puñetazo que MVLL propinó a García Márquez cuando el escritor colombiano venía a abrazar al novelista peruano.” Armas Marcelo 2002, p. 110 [Full cite: Armas Marcelo, J. J. (2002), Vargas Llosa, el vicio de escribir (in Spanish), Madrid: Alfaguara.]

[39] Dammann 2007 [Full cite: Dammann, Guy (10 January 2007), “Let’s hear it for literary feuds”, The Guardian, London.]

[40] Cohen 2007 [Full cite: Cohen, Noam (29 March 2007), “García Márquez’s Shiner Ends Its 31 Years of Quietude”, The New York Times.]

[41] Vincent 2007, p. 3 [Full cite: Vincent, Elizabeth (27 August 2007), “Interview with Mario Vargas Llosa”, Maclean’s, archived from the original.]