Buenos Aires, Mar 4 (PTI) 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 quarterfinals 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 has ranked way above at the 22nd spot in the ATP chart. Nagal will play Spain's Albert Ramos-Vinolas, in what will be the Indian's maiden quarterfinal appearance at the ATP Tour level. Ramos-Vinolas had defeated Dominik Koepfer of Germany 7-5 6-4.