BUENOS AIRES (REUTERS) - Unseeded Ukrainian Alexandr Dolgopolov upset favourite Kei Nishikori 7-6(4) 6-4 to win the Argentina Open on Sunday (Feb 19) and lift his first title in five years.

The 28-year-old Dolgopolov, who took one hour and 40 minutes to win the final at the Buenos Aires Lawn Tennis Club, earned his first victory over the Japanese world No. 5 at the sixth attempt.

Dolgopolov, the world number 66, lifted his third career ATP title by going through the clay court tournament without dropping a set.

The Ukrainian, whose previous crown came at Washington in 2012, the year of his career-high ranking of 13th, went toe-to-toe with Nishikori in a long first set that he clinched 7-4 in the tiebreak with his second set point.

He then broke his opponent for the first time when they were 3-3 in the second set with a winner from his potent backhand and went on to take victory with his first match point.

Top-seed Nishikori was looking for a 12th title, having won his last at Memphis last year, and now moves on to the Rio Open with Dolgopolov.

Dolgopolov ended a run of seven successive Argentina Open triumphs by Spanish champions in Buenos Aires as he succeeded last year's winner Rafael Nadal.