Manchester United misfit Alexis Sanchez scored for the first time in five months and provided an assist as Chile began their Copa America defense in emphatic fashion with a thumping 4-0 win over tournament guests Japan on Monday.

The 2015 and 2016 Copa champions took the lead late in the first half against a largely young and inexperienced Japan with a towering header from midfielder Erick Pulgar.

Journeyman striker Eduardo Vargas continued his remarkable consistency for his country by scoring in a fourth consecutive major tournament.

He doubled Chile's lead in the 54th minute with the help of a deflection.

Sanchez made it 3-0 with a diving header from close range in the 82nd minute, punching the air in celebration after enduring a frustrating season with United.

A minute later Sanchez laid on a pass for Vargas to score again, this time with a classy chip.