altidore made his professional debut on august 23, 2006, as a substitute in a 3–1 u.s. open cup loss to d.c. united. he scored his first professional goal at the age of sixteen with an 83rd minute, 28-yard shot to beat the columbus crew 1–0 on september 16, 2006. exactly one week later, on september 23, 2006, in a 4–3 loss to d.c. united, altidore scored again. scoring three times in seven appearances, including a crucial goal against chicago fire on september 30, 2006, altidore became a fan favorite. he scored the red bulls' only goal of their 2–1 aggregate loss to d.c. united in the eastern conference semifinals series when he headed in a cross in the second leg. with that goal, he became the youngest player to score in the major league soccer playoffs at 16 years, 337 days (breaking damarcus beasley's record by almost three years). altidore was also youngest to start in a major league soccer playoff match on october 21 against d.c. united (16 years, 349 days). he also scored two goals in a 5–4 win over los angeles galaxy on august 18, 2007.