India’s Sumit Nagal registered the biggest win of his career when he stunned second seed Cristian Garin of Chile in straight sets to enter the quarter-finals of the Argentina Open ATP 250 tournament here.

Nagal, ranked 150, produced high-class tennis on Wednesday to register an impressive 6-4, 6-3 second round win over his Chilean rival, who is ranked way above at the 22nd spot in the ATP chart.