Argentina's Sebastian Baez became the first back-to-back Rio Open champion by cruising to a 6-2, 6-3 victory over France's Alexandre Muller in the final of South America's biggest tournament on Sunday.

The fifth seed struck 26 winners and broke Muller's serve five times to take the match in an hour and 27 minutes on the outdoor clay of the Jockey Club Brasileiro.

"I'm so proud of the whole week," Baez said after the match. "I'm so happy with every match I played."

"Of course finals are different because you want to win the tournament. I try to focus on the match and that is the most difficult part in finals, but the support from my coach and the team was important in helping me to keep my focus."

It marked the 24-year-old's seventh ATP tour title, six of which have been on clay.

Muller, whose all-court game was so solid throughout the tournament, struggled from the outset against the world No. 31.

The 28-year-old's serve was particularly shaky as he committed three double faults while winning just 60 percent of points on his first serve and 32 percent on his second.

"He was physically superior to me. I had a great battle yesterday against [Francisco] Comesana," said the world No. 60, who was vying for his second ATP title.

"I tried to be aggressive, but he played very deep and it was difficult to move him. It was very tough for me today. I enjoyed my time in Rio, it was a great week, great matches and I hope to return next year," Muller added.

The Rio Open is the only ATP 500 tournament in South America and the sole ATP tour event in Brazil.