Tottenham quickly felt the absence of captain and talisman Heung-min Son as they edged into the FA Cup fourth-round with a narrow 1-0 win over Burnley.

As the clocked ticked towards an unwanted replay at Turf Moor, Pedro Porro's screamer 12 minutes from time was enough for Spurs, the Spaniard arrowing a dipping effort inside the post from 25 yards.

It was one of those nights where Spurs needed a moment of inspiration as they laboured to make the breakthrough without Son, who could miss up the six weeks at the Asian Cup with South Korea.

Son had called on his teammates to "step up" in his absence, just as he did whenever Harry Kane was missing through injury, while Ange Postecoglou warned his squad on the eve of the game that everyone would have to raise their levels to cope with the Korean's absence.

But faced with a spirited but struggling Burnley, the hosts were flat for long periods. Brennan Johnson was Spurs' liveliest attacker and tested Arijanet Muric in the Burnley goal four times while still lacking real conviction in the final third, while Dejan Kulusevski was quiet -- barring one curling effort which sailed just over.

Richarlison, meanwhile, had a difficult evening in his first game as Spurs' undisputed leading man up front, twice miscuing tame left-foot efforts in the first half and appeared out of sorts on the rare occasions the ball dropped to him in sight of goal.

It is easy to imagine that Son, who has 12 goals and five assists already this season, would have buried at least one of the openings, or provided enough spark to put Spurs in a comfortable position long before Porro's strike.

Postecoglou has said that Spurs attacking play is still their biggest area for improvement, and watching them lack cutting edge against a well-drilled Clarets side, you wondered how much Son's unerring ability to finish chances has made the difference so far this season.

It was, however, still a largely positive night for Spurs, who welcomed Micky van de Ven and Ryan Sessegnon back to the squad after hamstring injuries. Sessegnon made a late cameo -- his first appearance for 11 months -- while van de Ven was an unused substitute but may be fit to play at Manchester United on January 14.

While Postecoglou will be concerned about Spurs' forward play without Son for the game at Old Trafford -- and the fourth round later this month -- he will be pleased to avoid a replay or another early cup exit.

The Australian underlined his commitment to this competition by naming his strongest available XI, and will know that if Spurs can navigate the early rounds, they will be capable of going all the way -- particularly with Arsenal and Liverpool meeting in the third-round.

In the here and now, however, Spurs are clearly going to feel the loss of Son unless their other attackers can improve on this display.