Toronto FC scored two late goals to open a 2-0 advantage over New York City FC in a physical first leg of their MLS playoff series on Sunday night.
NYCFC held off a furious attack from Altidore and Sebastian Giovinco until the 84th minute, when the U.S. striker fired home from close range, and Tosaint Ricketts added a second in stoppage time.
Toronto threatened from the early stages and nearly scored in the 12th miute when Altidore played Giovinco in on goal, but NYCFC keeper Eirik Johansen made a point-blank save.
Giovinco tested Johnson again with a dipping free kick four minutes before half-time, but the Norwegian did well to push the ball away after a bounce.
NYCFC's first good opportunity came three minutes after the break when RJ Allen lashed a shot wide from the top of the box.
The hosts responded with a spell of extended pressure and had a Justin Morrow goal ruled out after it was adjudged to have come off Altidore's arm before he played it across to his teammate.
Drew Moor's diving header two minutes later looped off the bar -- the defender getting a kick to his face for his efforts.
The visitors were handed five yellow cards throughout the match, none more serious than when Mikey Lopez slid through Steven Beitashour. He was promptly replaced by Frank Lampard.
Toronto then had a penalty shout waved away as Maxine Chanot collided with Altidore, and Jonathan Osorio fired the loose ball over the bar.
Jack Harrison had a chance go astray in a rare period of possession for NYCFC, just before Altidore finally found the breakthrough in the 84th minute.
NYCFC had two chances to clear the ball as it bounced across the box, with Ricketts touching it on before it fell to Altidore to smash in.
The news got worse for the visitors when Ricketts found the net in the 92nd minute, poking home at the second attempt after Johansen's initial save to double Patrick Vieira's task for the return leg in the first-ever MLS playoff game at Yankee Stadium.