Swansea claimed the south Wales derby bragging rights with a 2-0 win over Cardiff.
Liam Cullen volleyed beyond Ethan Horvath – his sixth goal of the season – after 34 minutes in what was a dominant first-half showing from Swansea.
Cullen then missed a penalty in the 51st minute as Cardiff improved in the second half, but Jamal Lowe struck in injury-time to earn Luke Williams’ men all three points.
It ensured the Swans earned back-to-back home wins for the first time under Williams, while defeat ended Cardiff’s four-game winning run.
The Swans clearly meant business as they sought to avenge their 2-0 loss in the reverse fixture – with Harry Darling and Cullen having decent efforts early on.
Cardiff looked nervy and almost fell behind in the 16th minute when Jamie Paterson’s lofted cross found Darling unmarked, although the centre-back’s header crashed off the crossbar.
The hosts were left incensed moments later when Yakou Meite escaped a red card for pushing his head into the face of Darling.
The Bluebirds eventually showed signs of settling and saw Dimitrios Goutas poke wide from a David Turnbull corner.
But Swansea got the breakthrough their efforts warranted just after the half-hour mark following sublime work from January signing Ronald.
The Brazilian winger lifted the ball over Josh Wilson-Esbrand before darting 40 yards upfield and laying off to Kyle Naughton.
The experienced defender’s floated delivery found Cullen, who coolly volleyed beyond Horvath at the back post to send the home fans into raptures.
Ronald himself then rifled over as the Swans looked for a second, and Erol Bulut will no doubt have been pleased to reach half-time with his side only a goal down.
The Cardiff boss sent Rubin Colwill and Callum O’Dowda on for Turnbull and Meite, although they made a disastrous start to the second-half as Perry Ng conceded a penalty for dragging down Ronald.
However, first-half goal hero Cullen could only fire the spot-kick wide to give Cardiff hope.
The miss certainly lifted Cardiff’s spirits, with Nat Phillips heading at Carl Rushworth before Colwill lashed over as the visitors finally threatened.
Bulut’s men enjoyed more periods in possession as Ollie Tanner and Josh Key replaced Josh Bowler and Naughton respectively.
Ronald – now on the left flank – continued to show his quality though and beautifully picked out Cullen who headed wide.
Ollie Cooper, Lowe and Jay Fulton were all summoned from the bench, while Wales star Aaron Ramsey returned after a month on the sidelines with 19 minutes left on the clock.
The final stages were cagey as Horvath comfortably gathered Matt Grimes’ free-kick before Goutas headed over at the other end.
But Lowe rounded Horvath before drilling into the net in the sixth minute of added time as Swansea clinched a third successive home win over their neighbours, who lost ground in the race for a Sky Bet Championship play-off spot.