Swansea started the day in the play-off positions with only three league defeats all season and boasting the meanest defence in the Sky Bet Championship.

But Cardiff were actually in the richer vein of form with four successive wins propelling them into the top half of the division.

Swansea were ahead inside six minutes after Lowe, signed from Wigan in the summer, instigated a move which saw Cardiff fail to deal with Jake Bidwell's lofted cross from the left.

Connor Roberts beat Joe Bennett at the far post and Lowe met his header to score from six yards as his shot squirmed through the grasp of goalkeeper Alex Smithies.

Curtis Nelson sent a header straight at Freddie Woodman, but Swansea continued to dominate and Matt Grimes' superbly struck angled drive stuck a post with Smithies' touch proving decisive.

Cardiff instantly broke up the field and Ryan Bennett, booked earlier for a cynical block on Mark Harris, impeded Kieffer Moore on the edge of the penalty area.

Moore stayed on his feet and got his shot away, the striker's honesty perhaps keeping Bennett on the pitch.

Referee Jon Brooks did bring the play back and award a free-kick, which Harry Wilson harmlessly curled over the crossbar.

Even without fans the bitter rivalry between the two clubs surfaced in a flare-up between Moore and Marc Guehi and both players were cautioned.

Ayew's 30-yard snapshot tested Smithies and Swansea started the second half as they had finished the first, dominating possession and in complete command.

Moore's extravagant backheel, which actually bounced over the crossbar, led to his departure as the Wales striker was led away holding his hamstring.

Robert Glatzel replaced Moore and Sheyi Ojo fired over for the Bluebirds, but the game was generally becoming a scrappy spectacle with its rhythm disrupted by a succession of fouls.

Cardiff were reduced to 10 men midway through the second half when Ralls, having been booked for felling Jay Fulton straight after the restart, clattered into Korey Smith.

Referee Brooks had no hesitation in producing a second yellow card, although Ralls might have seen a straight red given the reckless nature of his challenge.

Lowe put the issue beyond doubt after 72 minutes with a superb solo goal, evading the challenges of Will Vaulks and Harry Wilson and finishing from 18 yards with the outside of his foot.