Dele Alli scored the winning goal as Tottenham edged out Barnsley to reach the Carabao Cup fourth round in front of a Wembley crowd of just 23,926.
Alli struck from six yards out in the second half following excellent work by full-back Kieran Trippier.
Striker Fernando Llorente, making his first Spurs start, headed wide from a promising position in the first half.
Championship Barnsley had chances but Liam Lindsay headed wide and Ike Ugbo struck straight at Michel Vorm.
Spurs manager Mauricio Pochettino said before the game that prioritising domestic cups over the Premier League or Champions League would be “a big mistake”.
But the Argentine fielded a strong starting line-up, containing Alli, Jan Vertonghen and Mousa Dembele, with top scorer Harry Kane on the bench.
Pochettino’s apparent lack of enthusiasm for the competition was shared by Spurs supporters, with the 90,000-seater national stadium less than one-third full.
Spurs had won just one game – against Borussia Dortmund – at Wembley all season, and this game looked like being another one that would slip away from them.
Debutant Juan Foyth should have scored in the opening minutes, but nodded off target with a free header, and Alli headed wide from Harry Winks’ chipped pass into the box.
But England international Alli netted on 65 minutes as Spurs claimed their 18th win from their past 19 home League Cup games against sides from a lower division.
Paul Heckingbottom’s Barnsley are struggling at the wrong end of the Championship after collecting just seven points from their opening seven league games.
In their last game, they were thumped 3-0 by Aston Villa, leaving them three points above the relegation zone.
But they can take heart from an impressive showing against one of the Premier League’s best sides and should have gone ahead through Lindsay and on-loan Chelsea forward Ugbo.
The South Yorkshire side face another tough game on Saturday when they travel to Molineux to face promotion-challenging Wolves.