Iranian international Mehdi Taremi salvaged a point for defending champions Porto in a 1-1 draw with long-time rivals Benfica on Friday.
However, Taremi’s night ended in misery when he was sent-off in the 73rd minute for a poor challenge on Nicolas Otamendi.
Spanish defender Alex Grimaldo had put Benfica in front after just 17 minutes at the Estadio do Dragao, finishing off a fine pass from Haris Seferovic.
The lead lasted just eight minutes before 28-year-old striker Taremi brought Porto level with his seventh league goal of the season.
Both sides, who have 66 league titles between them and have monopolised the championship for the last 18 years, remain four points behind leaders Sporting Lisbon.
Sporting was held 1-1 by Rio Ave for whom former Lisbon star Gelson Dala scored on the hour mark.
Pedro Goncalves had put undefeated Sporting ahead in the 42nd minute with his 12th goal of the season.