Uruguay opened the scoring in the top-of-the-table clash on Thursday but the hosts were unable to stop a rampant Brazil, who were led by Paulinho's hat-trick and Neymar's stunning lob.
The result saw Brazil move seven points clear of second-placed Uruguay in the CONMEBOL standings as Tabarez's men lost a World Cup qualifying match at home for the first time since 2009 - a run of 14 games.
"It hurts, although we are professionals we have passion for this and when we do not get what we want, it hurts," Tabarez said post-match after being without suspended duo Luis Suarez and Fernando Muslera.
"Sometimes these hard knocks give us a clearer picture of where we are.
"You never know what you're going to find in a football game. [The result] was not one of the possibilities I considered to be more likely.
"There is nothing to say, Brazil defended very well and were very forceful."
Uruguay are back in action on Tuesday, travelling to Peru.