AREQUIPA, Peru, Dec 19 (Reuters) - Cienciano became the first Peruvian club to win an international competition when they beat River Plate 1-0 to capture the Copa Sudamericana despite finishing the second leg with nine men on Friday.

Cienciano, a modest provincial team who have never won their domestic championship, had Juan Carlos La Rosa and Julio Garcia sent off in the second half as they overcame the Argentine giants 4-3 on aggregate.

It was Peruvian soccer's first international title at any level since the national side won the Copa America in 1975.

Cienciano, who ousted Brazil's Santos in the quarter-finals, upstaged the Lima trio of Sporting Cristal, Alianza Lima and Universitario, who have traditionally dominated Peruvian soccer without winning an international trophy between them.

The closest they came was in 1997 when Cristal were beaten by Brazil's Cruzeiro in the final of the Libertadores Cup, the South American equivalent of the Champions League.

Paraguayan defender Carlos Lugo scored Cienciano's winner in the 77th minute to spark wild celebrations among the 44,000 crowd.

Cienciano are based in the ancient Inca city of Cusco but were forced to play the final in Arequipa because their own stadium was considered too small to host a South American final.

La Rosa was sent off for a second bookable offence six minutes into the second half. Four minutes from time, the Red Fury also had Garcia dismissed for the same reason.

The Copa Sudamericana, which is being played for the second time, is the South American equivalent of the UEFA Cup.

Argentina's San Lorenzo won the inaugural tournament last year.