The career of apprentice jockey Junior Chacaltana is heating up. He cracked the top 10 in the Sam Houston Race Park rider standings last week, after recording a double on Sunday and a triple on Feb. 9. The 22-year-old native of Lima, Peru, launched his riding career last July, with the support of trainer Brent Davidson. Other high-percentage horsemen he is riding for this meet include Danny Pish and Randy Mayfield.