Unseeded Argentine teenager Juan Martin del Potro upset French second seed Richard Gasquet 6-4 7-5 to win the Stuttgart Cup claycourt event on Sunday.
The towering 1.95-metre tall world number 65 benefited from some erratic play by the French number one to deservedly clinch his first ATP title.
"I knew I had to serve well to win, and now I can just enjoy it."
Del Potro showed resilience and steady nerves in both sets.
After breaking Gasquet early on in each, he was pulled back to level terms in the subsequent games.
Rather than folding, he responded with further decisive breaks against the world number 15 in the penultimate game of each set, serving out to love at the end of the second to wrap up his win.
"For sure I want to congratulate him on his first title," said Gasquet, a former world number seven who has gone 10 months since winning his fifth career title in Mumbai last September.
Tommy Robredo breaks season drought with Bastad win
Spanish third seed Tommy Robredo captured his first title of the season at the Swedish Open here on Sunday with a comfortable 6-4, 6-1 win over fourth-seeded Czech Tomas Berdych.
It was the second title in Bastad for Robredo, who was also champion in 2006, and the seventh of his career.
"I am obviously very happy to have won the title here in Bastad once again," said the 26-year-old.
Berdych said he was hampered by a painful knee as the final progressed.
"I felt something in my knee in the sixth game of the match when I was down 3-2," said the fourth seed.
In the semi-final, Robredo had defeated top seed and defending champion David Ferrer, while Berdych saw off second-seeded Spaniard Fernando Verdasco in the first time since 1984 that the top four seeds had completed the semi-final line-up.