South America Results: Nobby nets again in Peru
Ecuadorean champions Deportivo Quito lost 4-0 to local rivals LDU in a game they had threatened to boycott over a pay dispute.
Melgar snatched a point in amazing circumstances after drawing 1-1 away to newly-promoted Inti Gas.
The hosts, who had Jean Tragodara sent off after only nine minutes for a rough challenge, appeared set for their first win of the season when Mario Velarde scored from a free kick in the 88th minute.
The referee was surrounded by a furious Melgar team and media reports said one player appeared to push one of the policemen who came onto the field to protect the official.
Melgar coach Claudio Techara was sent off and his team at one stage threatened to abandon the match as play was held up for five minutes.
When the game re-started, Inti Gas lost concentration and Gerardo Gerarte equalised in the seventh minute of injury time after being left completed unmarked.
Former Newcastle United, Aston Villa, West Ham United and Boca Juniors midfielder Nolberto Solano converted a last minute penalty to give Universitario a 1-1 draw at Cienciano, who went ahead with a Mauricio Romero penalty after half an hour.
Paraguayan striker Richard Estigarriba scored four goals in Total Chalaco's 4-0 win over Jose Galvez.
Titleholders Deportivo Quito, who agreed to face LDU after being paid outstanding wages on Friday, crashed to a 4-0 defeat.
Walter Calderon and Argentine Claudio Bieler put LDU, the reigning South American champions, 2-0 ahead in only five minutes and Bieler added a third before halftime.
Deportivo defender Giovanni Caicedo put through his own goal in the second half.
Guayaquil rivals Emelec and Barcelona both remained winless after five games of the 2009 championship following their 0-0 draw in the Shipyard derby at the Capwell stadium.
Emelec are bottom after picking up their first point while Barcelona have four points, all from draws, under former Real Madrid coach Benito Toro.
Tolima's match at home to Atletico Nacional was interrupted early on when visiting fans clashed with fans outside the stadium and the wind blew tear gas across the pitch.
Several players were treated before play resumed.
Sergio Galvan gave Atletico a halftime lead but Tolima, who nearly pulled out of the championship because of chronic financial problems, replied with second-half goals from Rodrigo Marangoni and Wílder Medina.
The defeat left Atletico, one of Colombia's most popular clubs, bottom of the Apertura championship after losing all five games under former Ecuador coach Luis Fernando Suarez.
Titleholders America lost 1-0 to arch-rivals Deportivo Cali, where And