BUENOS AIRES, Jan 15 (Reuters) - River Plate lost 3-2 to arch-rivals Boca Juniors in a pre-season tournament in their first match under new coach Daniel Passarella.
Rodrigo Palacio scored either side of halftime in Saturday night's match in Mar del Plata to put Boca, who won the Apertura championship which finished in December, in the driving seat before a 35,000 crowd.
Midfielder Daniel Montenegro replied for River in the 58th minute but Daniel Diaz restored Boca's two-goal lead 15 minutes later when he scored direct from a free kick.
Leandro Fernandez pulled another back for River in the 90th minute.
Passarella, who captained Argentina's 1978 World Cup-winning side, returned for a second stint when he signed with the club on Tuesday, replacing Reinaldo Merlo who resigned the day before after only four months in the job.
Passarella had previously coached the team from 1991 to 1994.
Boca and River are due to meet again in the northern city of Salta on Tuesday.