Almagro, 25 and a professional since 2003, has been inching up the rankings since last July, moving up one or two spots -- and never slipping back -- and reached No. 10 for the first time in rankings updated Monday.
He's 25-7 this year with wins at Costa Do Sauipe, Brazil, and Buenos Aires. He was second at Acapulco, Mexico, and lost to David Ferrer in the semis last week in Barcelona, Spain.
His move into the Top 10, dropping top American Mardy Fish to 11th, was the only change in the Top 10 this week.
Rafael Nadal, 29-4 this year after beating Ferrer in the finals Sunday at Barcelona, has 12,870 rankings points and tops the rankings for the 48th consecutive week while Novak Djokovic sits at No. 2 with 9,640 points. Roger Federer (8,550) remains third, Andy Murray (5,905) is fourth and Robin Soderling (5,175) is fifth.
Ferrer has 4,840 rankings points and holds the No. 6 spot with Tomas Berdych (3,900) seventh, Jurgen Melzer (3,020) in eighth and Gael Monfils (2,600) in ninth ahead of Almagro (2,530).
Djokovic, playing the Serbia Open, and Soderling, seeded first at Portugal's Estoril Open, are the only Top 10 players in action this week.