Match ends, Tottenham Hotspur 1, Barnsley 0.
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 spared more Wembley woe
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.
Brave Barnsley can take heart
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.
- 19DembéléSubstituted forDierat 79'minutes
- 20AlliSubstituted forOakley-Bootheat 90+2'minutes
- 7Son Heung-Min
- 18LlorenteSubstituted forNkoudouat 67'minutes
- 20PottsSubstituted forMoncurat 71'minutes
- 4WilliamsSubstituted forBradshawat 79'minutes
- 15BarnesSubstituted forHammillat 71'minutes
- Tim Robinson
- Shots on Target
Second Half ends, Tottenham Hotspur 1, Barnsley 0.
Attempt missed. Harry Winks (Tottenham Hotspur) right footed shot from outside the box is high and wide to the right. Assisted by Son Heung-Min following a corner.
Corner, Tottenham Hotspur. Conceded by Jason McCarthy.
Attempt blocked. Son Heung-Min (Tottenham Hotspur) left footed shot from outside the box is blocked. Assisted by Georges-Kévin Nkoudou.
Substitution, Tottenham Hotspur. Tashan Oakley-Boothe replaces Dele Alli.
Offside, Barnsley. Jason McCarthy tries a through ball, but Adam Hammill is caught offside.
Foul by Kieran Trippier (Tottenham Hotspur).
Jared Bird (Barnsley) wins a free kick in the defensive half.
Delay over. They are ready to continue.
Delay in match Ezekiel Fryers (Barnsley) because of an injury.
Corner, Tottenham Hotspur. Conceded by Adam Davies.
Attempt saved. Son Heung-Min (Tottenham Hotspur) right footed shot from the right side of the box is saved in the top right corner. Assisted by Kieran Trippier.
Kyle Walker-Peters (Tottenham Hotspur) wins a free kick in the defensive half.
Foul by Adam Hammill (Barnsley).
Foul by Eric Dier (Tottenham Hotspur).
Adam Hammill (Barnsley) wins a free kick on the right wing.
Attempt saved. Son Heung-Min (Tottenham Hotspur) left footed shot from a difficult angle on the left is saved in the bottom left corner. Assisted by Moussa Sissoko.
Attempt blocked. Adam Hammill (Barnsley) right footed shot from outside the box is blocked.
Attempt missed. Liam Lindsay (Barnsley) header from very close range misses to the left. Assisted by Ryan Hedges with a cross following a corner.