The Dodgers signed infielder Ramon Martinez to a minor-league contract today and invited him to big-league spring training, where he will be given a shot to compete with youngsters Tony Abreu and Chin-lung Hu for what probably will be two utility infield spots on the opening-day roster. Martinez, 35, spent the past two seasons with the Dodgers, hitting a combined .243 with two homers and 51 RBI. Both of those homers came in 2006, the first as part of a five-RBI performance at Atlanta on Memorial Day, the second a walkoff shot to end a 16-inning game with Cincinnati on Aug. 29. He slumped to a .194 average in 2007 while appearing in just 67 games. Martinez received $850,000 last year. He is a 10-year major-league veteran who has spent his entire career as a reserve player.