A goal just before the hour mark after sloppy defending by Tottenham was enough to give Gent the advantage going into next week's Europa League round-of-32 return leg at Wembley Stadium.
Mauricio Pochettino had fielded a near full-strength team, hoping to get a reaction after last Saturday's defeat in the Premier League to Liverpool at Anfield, but Spurs started sluggishly and only managed one decent shot on target in the first half. Tottenham improved briefly at the start of the second half and went close to taking the lead when Harry Kane hit the outside of the post.