Donny van de Beek scored the only goal of the game in the 15th minute after a superb interchange of passes in front of Spurs’ box saw him go one on one with Hugo Lloris who he beat from close range.
It was a game Ajax deservedly won as they dominated most part of the match with Spurs mustering just one shot on target, their joint-fewest total in a Champions League game.
Ajax are now unbeaten in six Champions League away games this season.
The return leg comes up next week Wednesday at the Amsterdam Arena.
The other semi-final of this season’s Champions League will see Barcelona host Liverpool at the Nou Camp on Wednesday.