In Spanish-speaking countries, instead of Friday, Tuesday the 13th is considered a day of bad luck, commonly referred to as ‘Martes y trece‘ (Literally translates to: Tuesday and thirteen).
The Greeks also consider Tuesday (and especially the 13th) an unlucky day. Tuesday is considered dominated by the influence of Ares, the god of war. A connection can be seen in the etymology of the name in some European languages (Mardi in French or martes in Spanish).
The fall of Constantinople to the Fourth Crusade occurred on Tuesday, April 13, 1204 and the Fall of Constantinople to the Ottomans happened on Tuesday, May 29, 1453, events that strengthen the superstition about Tuesday.
In addition, in Greek the name of the day is Triti (Τρίτη) meaning literally the third (day of the week), adding weight to the superstition, since bad luck is said to “come in threes”.
Found at Wikipedia