The striker is in red-hot form, and is now one goal away for setting a record for Americans in Europe.
With his 23rd goal of the season in all competitions, Altidore tied Clint Dempsey's mark for most goals scored by an American in Europe. Dempsey set the record last season with Fulham.
The striker opened the scoring in the 74th minute with a close-range header. Altidore then assisted teammate Johann Berg Gudmundsson in the 88th minute, after holding the ball up and playing a brilliant ball past the Ajax defense.
He wasn't done though, adding an audacious chipped goal from 35 yards out with nearly the last kick of the match to make the final score 3-0.
AZ advances to the final with the win, where it will take on PSV. Altidore's first chance to break Dempsey's record will come Sunday against Waalwijk in league play.