BARCELONA, Spain (AP) -- Top-seeded Kei Nishikori began the defense of his Barcelona Open title with a 6-3, 6-4 victory over Teymuraz Gabashvili of Russia on Tuesday.
Nicolas Almagro also advanced to the second round, where he will face eight-time winner Rafael Nadal, after opponent Paolo Lorenzi retired 10 minutes into the match with Almagro leading 3-0. Last year, Almagro stunned Nadal in the quarterfinals, ending Nadal's run of 41 straight wins at the tournament.
Nishikori hit 22 winners and held his serve to win the second-round match on the outdoor clay court in one hour, eight minutes.
The fifth-ranked Japanese player could face last year's runner-up Santiago Giraldo on Thursday if the Colombian gets past Joao Sousa.
Nishikori took control of the match by hitting 11 winners and breaking Gabashvili before finishing out the first set by holding his final serve to love.
Gabashvili tossed his racket down after a third double fault cost him his service as he fell behind 3-2 in the second set. Nishikori then struck an ace to finish the match.
''It was a great first match,'' Nishikori said. ''It was my first match of the year on clay, so I was little tight, but I played a great two sets today.''
In the day's other second-round matches, seventh-seeded Roberto Bautista Agut advanced after beating Thomaz Bellucci 6-3, 6-4, while Tommy Robredo downed Mikhail Kukushkin 6-3, 6-2.
Earlier, Russian teenager Andrey Rublev beat 2010 champion Fernando Verdasco 7-6 (4), 6-3 in the first round.
The 17-year-old Rublev, who entered as a qualifier ranked 329th, broke the Spaniard three times while saving five break chances. Rublev will next face 13th-seeded Fabio Fognini.
Albert Montanes also came back to defeat Ricardas Berankis 1-6, 6-4, 7-5 and will meet David Ferrer in the second round, where 2014 U.S. Open winner Marin Cilic will play Victor Estrella after Estrella ousted Dominic Thiem 6-3, 7-6 (3).
Juan Monaco got past Alejandro Gonzalez 7-5, 6-1 and will play Martin Klizan, while Pablo Cuevas beat Roberto Carballes Baena 6-4, 7-5.
Marsel Ilhan outlasted James Ward 7-6 (2), 3-6, 6-1 in just over two hours, while Sousa edged lucky loser Kenny de Schepper 6-4, 3-6, 6-3.