Wayne Routledge has scored three goals this season
Swansea City comprehensively outplayed Middlesbrough to consign them to a sixth successive defeat and increase the scrutiny on manager Tony Pulis.
The Swans played joyful attacking football in the first half, overwhelming their opponents with their pace and movement to lead 2-0 thanks to Matt Grimes' penalty and Wayne Routledge's neat low finish.
The second half was a stroll for the hosts, who added a third as Bersant Celina's artfully disguised cross to the back post was volleyed in by Connor Roberts, rendering George Saville's late volley for Boro academic.
Swansea's fourth consecutive home win keeps intact their slim hopes of making the play-offs, lifting them up to 13th in the Championship table and nine points behind the top six but with a game in hand on most of their rivals.
For Boro, however, losing a sixth straight game for the first time since 2000 is another blow to their play-off prospects, leaving them eighth in the table and four points adrift of sixth place.
Boro fans had called for Pulis to be sacked during Tuesday's 1-0 loss at home to Bristol City but chairman Steve Gibson was reportedly willing to stick by the Welsh boss until the end of the season.
With a gap of then only two points between Boro and the top six, they still had hopes of challenging for promotion.
But those prospects looked increasingly vulnerable in south Wales as the visitors were undone by a Swansea side who bossed possession and created a hatful of good chances to take the lead.
Celina was the first to threaten, brilliantly controlling a Nathan Dyer cross but lifting his shot over the bar.
The electric Daniel James then cut inside and sent a powerful effort whistling just wide, before Celina threaded a beautiful pass through to Routledge, who had the whole goal to aim for but wastefully blasted the ball at the bar.
James played a prominent role in the opening goal, darting into the penalty area and drawing a foul from Ryan Shotton, who had only just come on to the field as a substitute for the injured George Friend.
Grimes confidently converted his penalty and the floodgates opened.
Five minutes later, Celina produced another fine through ball for Routledge but this time the Swansea winger composed himself and steered his shot into the bottom corner.
The home side could have had a third before the break, James picking up possession in his own half and speeding past Boro's hapless defenders before curling another effort wide.
Swansea eased up a little in the second half but still controlled the tie, with Celina's beautifully weighted cross well met by a sliding Roberts, who had endured an unhappy loan spell with Middlesbrough last season.
The visitors at least had something to cheer late on when, from a half-cleared corner, Saville thumped his volley into the roof of the net.
Boro's players barely celebrated and, although they enjoyed more possession in the closing stages, this latest defeat was another setback to their play-off hopes and another blemish for the increasingly under-fire Pulis.
Swansea manager Graham Potter told BBC Sport Wales:
"I am very pleased, it is not easy to create chances or score against Middlesbrough with how they defend.
"We were excellent first half with our attacking play. We had a good understanding of what we were trying to do, we scored two good goals and probably could have added to that.
"Getting the third was important, you know you need it as they can put balls in the box and it is dangerous as it proved with their goal.
"It was more nervy than needed to be at the end, but overall we completely controlled the game, we were the better team and deserved the win."
Middlesbrough boss Tony Pulis said:
"I am really disappointed. In the first half our tempo and decision-making were awful.
"We should have had a penalty in the second half for a clear handball.
"Swansea were a Premier League side last season and this was the game I was more worried about than all the others.
"Five games to go and it is all to play for."
