BUENOS AIRES, April 13 (Reuters) - River Plate beat Tigre 1-0 in a near deserted Monumental stadium on Sunday to stay top of the Argentine championship. River were barred from selling tickets for the game, except to club members occupying the most expensive seats, following crowd violence at a match against Arsenal two weeks ago. Colombian striker Radamel Falcao Garcia headed the winner from a Matias Abelairas cross five minutes after halftime. River had midfielder Oscar Ahumado sent off for a second bookable offence in the 55th minute and the visitors had Santiago Morello dismissed five minutes later. 'It was a strange game with a lot of wind and not many people,' said River coach Diego Simeone. 'It was sad to see the empty stands but we have to obey the law and hope that it will be for the better.' Boca Juniors and Estudiantes both won to stay four points behind Simeone's team, who have 24 points from 10 games and are still unbeaten. Jesus Datolo scored both goals to give Boca a 2-1 win at Gimnasia-Jujuy, who pulled one back through Luis Escalada late in the game. Estudiantes beat Lanus 1-0 on Friday with a goal by Juan Sebastian Veron. Racing Club celebrated Juan Manuel Llop's debut as coach by winning for the first time, a spectacular free kick from Franco Sosa giving them a 1-0 win over Arsenal. Racing, one of Argentina's most fanatically supported clubs, are 18th in the 20-team table. Their plight has brought heavy criticism on Blanquiceleste S.A., the independent management company brought in to run Racing after the club nearly folded in 2000.