Messi and Suarez lead Barcelona to Club World Cup title
Luis Suarez, Lionel Messi and Neymar were all in fine form as River Plate struggled to cope with the star trio.
Messi opened the scoring when he controlled Neymar's pass to finish and Suarez added two more as the Catalan side cruised to victory.
Uruguay striker Suarez finished the tournament with five goals in two games after adding to the hat-trick he scored in the 3-0 semi-final win over Guangzhou Evergrande.
For manager Luis Enrique the victory capped a remarkable 2015. Less than 12 months ago he was rumored to be on the verge of being sacked, but has since led Barca to five of the six possible trophies 2015 had to offer.
Having also hoisted La Liga, the Copa del Rey, Champions League and European Super Cup crowns during 2015, only a Spanish Super Cup defeat by Athletic Bilbao denied Barcelona the chance to match the 2009 sextuple achieved under Pep Guardiola.
The Catalans are currently top of La Liga with a game in hand, and are in the last 16 of the Copa del Rey and Champions League - as they bid to do it all again in 2016.
"To finish the year with a fifth title - it was a clear goal for us," Enrique said. "In football it is increasingly difficult to win. What matters is the way [the players] earn titles, not just the number of titles, but the way they win.
"Barca's style remains appealing to anyone who loves football. These players are unique. They are brilliant on a human level. They have put in a tremendous effort here and it is something to be proud of."
Barcelona have scored 176 goals this year - a new club record. They play Real Betis in the league on December 30 in their final game of the calendar year, with a chance to push the tally higher.
River Plate started brightly in the Yokohama International Stadium, pressing their more illustrious opponents and making life difficult all over the pitch. However, once Messi, Suarez and Neymar sprang into life there was only going to be one result.
For Barca's opener Neymar and Messi both had roles in the build-up before the Brazilian found his Argentine teammate to fire home the opener.
Suarez added a second from Sergio Busquets' excellent long ball and then headed home Neymar's superb cross for his second.
Suarez and Messi tried to play in Neymar for a goal of his own, but despite not scoring, the Brazilian will still be happy with his performance - having lost in the 2011 final to Barca while at Santos.
River Plate: Barovero, Mercado, Maidana, Balanta, Vangioni, Kranevitter Sánchez, Viudez (Driussi - 56'), Ponzio (Lucho - 45'), Mora (Martínez - 45'), Alario.
Substitutes: Vega, Martínez, Saviola, Batalla, Pisculichi, Bertolo, Mayada, Casco, Driussi, Mammana, Chiarini, Lucho.
Barcelona: Bravo, Dani Alves, Piqué, Mascherano (Vermaelen - 81'), Alba, Rakitic (Sergi - 67'), Busquets, Iniesta, Messi, Suárez, Neymar (Mathieu - 89').
Substitutes: ter Stegen, Bartra, El Haddadi, Ramírez, Sergi, Adriano, Vermaelen, Mathieu, Masip, Samper, Gumbau.