The Spurs team-mates both played the full 120 minutes as the game went into extra time after a goalless draw in Auckland, New Zealand.
Serbia edged it over the 120 minutes but the match went to a penalty shoot-out.
Both Spurs players stepped up in what turned into a dramatic shoot-out.
The teams missed a penalty each as the first five penalties ended 4-4 to take the shoot-out into sudden death.
With the USA taking first, Cameron missed their eighth penalty to leave Milos the chance to take Serbia through - only to see his spot-kick saved.
However, Pedrag Rajkovic saved USA's ninth penalty from John Requejo and that left Nemanja Maksimovic the chance to win it, and he delivered to take Serbia through 6-5.
Milos, who has played every minute of the tournament, will now line-up against Mali in the semi-finals in Auckland on Wednesday (7.30pm local time, 7.30am UK). Brazil face Senegal in the other semi-final in Christchurch.