Violence also marred a first division match in Venezuela, where sporting passion is more commonly associated with baseball.
A teenage player for third division Cerro, who was suspended and not involved in Saturday's match against Palomar, was knifed when an enraged man attacked several people leaving the stadium in the northern department of Salto, 500 km (310 miles) from Montevideo.
He died on Sunday night and the 31-year-old man, who had been involved in fighting between groups of rival fans, was arrested, Salto police told Reuters on Monday. A fan was in serious condition with knife wounds.
It was the second football-related death this month in Uruguay. A fan died of gunshot wounds early this month after incidents at an amateur second division match in Canelones close to the capital.
A fan of first division Cerro in Montevideo died following an attack by Penarol fans after a match at the Centenario four years ago. Two years ago a Nacional fan died after incidents following a match against Defensor Sporting.
In the top flight Apertura championship, Nacional extended their unbeaten run under coach Juan Ramon Carrasco with a 2-1 win over Danubio despite having two players sent off and climbed into joint second place.
Centre-back Gonzalo Godoy was dismissed for a second booking in the 66th minute with Nacional already 2-0 up and midfielder Robert Flores followed him off for a foul in the 80th, three minutes after defender Damian Malrrechaufe had pulled one back for Danubio.
Defensor Sporting beat champions Penarol 1-0 to open a four-point lead with two matches to go and could be crowned next weekend - when they are at home to Nacional.
One of the season's best matches, in which champions Caracas FC were held 2-2 by 10-man Deportivo Petare at the Olympic stadium in the capital, was marred at the end by fighting between home fans and police.
Fans broke seats, threw bottles and set off fireworks while police reacted with force, according to media reports.
Petare played the last 19 minutes a man short after goalkeeper Alan Liebeskind was sent off for bringing down Luis Cabezas.
With three substitutions already made, defender Andres Sanchez went in goal. He saved Dario Figueroa's penalty but Josef Martinez netted the rebound to make the score 1-1.
Caracas went ahead through Cabezas but Petare equalised with a controversial penalty five minutes from time converted by Evelio Hernandez, his second goal of the match, which sparked the violence in the stands.
"The referee scored the equaliser," an angry Figueroa was quoted by local media as saying.
There were problems in Real Esppor's visit to Carabobo where the match, which ended 0-0, was played behind closed doors after the home side's fans had caused trouble the previous weekend.
Fans of Carabobo turned up outside the stadium looking for a fight, causing the match kick-off to be delayed by 35 minutes.
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