The flying winger led the charge on a breakaway midway through the second half, bursting out of defence all the way into the Swans box before firing home to make it 3-1 at that stage, and although the visitors scored late on through former Spur Gyfli Sigurdsson, we held on to take the points.
Nacer Chadli set the ball rolling in the seventh minute with a tidy finish to put us ahead, before Swansea levelled things up on 20 minutes through Ki Sung-Yeung. But Ryan Mason opened his Premier League goalscoring account for us six minutes after the break to restore our lead, which was extended further on the hour mark through Townsend. Sigurdsson’s 88th minute goal proved to be just a late consolation for Garry Monk’s side.
Mauricio Pochettino kept faith with the XI the started Sunday’s Capital One Cup Final and we began brightly, playing with a high tempo and crisp passing as we looked to make a fast start to the contest.
And we did just that with the opening goal on seven minutes from our first real attack of note. Danny Rose picked the ball up wide on the left and sent over a teasing cross which evaded Harry Kane’s head, but it fell to Chadli who cushioned a neat volley past Lukasz Fabianski's out-stretched hand and into the net.
However no sooner had the celebrations died down than there was real concern as Swansea striker Bafetimbi Gomis collapsed with no-one near him just as the visitors were about to restart the game. Medical staff from both teams rushed onto the pitch and there was a lengthy delay as Gomis – who reportedly fainted - received treatment, eventually leaving the arena on a stretcher with an oxygen mask on. He was replaced by Nelson Oliveira.
The game resumed six minutes later and we were on the front foot again on 17 minutes, Nabil Bentaleb popping a pass in to Christian Eriksen, he flicked onto Townsend who tested Fabianski with a 20-yard drive which was comfortable for the keeper.
Within two minutes though Swansea were level. The returning Sigurdsson fired a 25-yard free-kick against the post, the visitors kept the ball alive and from the second phase of play, Ki skipped past Jan Vertonghen near the byline inside the area and slid the ball under Hugo Lloris.
It became a fairly even contest for the second half of the first 45 minutes, both sides probing and trying to create openings, Swansea mostly hitting us on the counter but always a threat as they surged forwards.
We were working hard to break them down, Mason and Bentaleb both testing Fabianski from distance while a flurry of crosses were delivered from either flank but none of them found a Spurs target well-placed to score and it was all square at the interval.
It was the visitors who had the first opportunity of the second half, Lloris palming Jonjo Shelvey’s 20-yard drive up and over the bar, while at the other end another Rose centre this time found Kane but he just missed the far post with a header back across goal.
Then on 51 minutes we were back in front with a well worked goal. Rose clipped a pass inside from the left touchline which Eriksen picked up and burst forwards, moving across the pitch. As he was tackled the ball found its way to Mason, who took a touch inside the area and smashed high into the net past Fabianski.
There was drama at both ends around the hour mark, with chances falling to both sides, ours ultimately seeing us extend our lead. First Swansea had a corner which Sigurdsson delivered, the ball was drilled goalwards but kept out by a fine diving save from Lloris. The Swans kept the ball alive but Bentaleb headed the danger away, fouled by Wayne Routledge as he did.
With the ball falling nicely for Townsend, referee Michael Oliver allowed the advantage to be played and the England winger put the burners on as he roared forwards down the left, into the area before cutting back onto his right and firing into the net. That was the 700th Premier League goal of this season!
We were well on top at this stage and Kyle Walker and Kane both saw efforts deflected for corners as we searched for a fourth. It so nearly arrived with 10 minutes remaining as Walker fizzed in a cross which substitute Roberto Soldado glanced goalwards, missing the far post by inches.
And the Spanish forward was a similar distance away from getting his foot on an inviting Ben Davies cross in the 87th minute, the former Swansea man played in by a neat Chadli flick down the left.
The visitors weren’t finished though and pulled a goal back just moments later when Jefferson Montero’s cross came to Sigurdsson and he tucked home to ensure an anxious last few minutes.
And a game which was seemingly done and dusted almost slipped away in the dying seconds as Swansea mounted a spell of late pressure, Montero again crossing from the left, Federico Fernandez this time getting on the end of it and producing a header which was creeping inside the post before Lloris flung himself across his goal to claw it away.
But we held on to pick up three crucial points.
Spurs (4-2-3-1): Lloris, Walker, Vertonghen, Dier, Rose (Davies 78), Mason, Bentaleb, Townsend (Dembele 65), Eriksen, Chadli, Kane (Soldado 76). Substitutes (not used): Vorm, Chiriches, Paulinho, Lamela.
Swansea (4-3-3): Fabianski, Naughton, Williams, Fernandez, Taylor, Cork, Shelvey (Montero 73), Ki, Routledge, Gomis (Oliveira 12), Sigurdsson. Substitutes (not used): Tremmel, Amat, Britton, Emnes, Rangel.
Goals: Spurs – Chadli 7, Mason 51, Townsend 60; Swansea – Ki 20, Sigurdsson 88.
Yellow cards: Spurs – Dier.
Referee: Michael Oliver.