Match ends, Swansea City 1, Cardiff City 0.
Swansea City earned the bragging rights in south Wales with a deserved 1-0 victory over a lacklustre Cardiff City.
Ben Wilmot was the hero in his first league start for Swansea, heading home from a cleverly worked short corner on 27 minutes.
Cardiff were a long way short of their best and chances for the visitors were few and far between at Liberty Stadium.
Swansea rise to fourth in the Championship, with Cardiff 14th and seven points behind their arch rivals.
This was the first south Wales derby since Swansea hammered Cardiff 3-0 in 2014, but few people would have expected a similar score in this contest.
The pre-match talk, with Swansea losing three and winning none of their last four home matches and making six changes, was that the hosts looked more than a little vulnerable heading into the derby.
But they were entirely dominant in the first period as they threw the script out of the window.
Boss Steve Cooper opted to play his experienced heads, with veterans Wayne Routledge and Nathan Dyer - survivors of the last meeting between the sides five year ago - both selected and Kyle Naughton recalled in place of Connor Roberts.
The Bluebirds, whose two changes were enforced by injury, were second to every ball in the first period and might have trailed inside 10 minutes, but Lee Peltier was able to make a last-ditch block on Ayew's teasing cross as the decibel level at Liberty Stadium proved undiminished by Wales' Rugby World Cup semi-final defeat earlier in the day.
Nathaniel Mendez-Laing fired over for Cardiff and easily looked their biggest threat, but chances for the Bluebirds were few and far between.
Swansea fired another warning shot when Matt Grimes' vicious effort skimmed the top of the bar, before their breakthrough came from an unlikely source, a set-piece.
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Wilmot beats Cardiff statues
It was supposed to be Cardiff with the aerial advantage, but they stood statuesque as Wilmot reacted quickest to a well-worked corner that allowed Routledge time to pick his pass and Wilmot headed across goal to give the hosts the lead.
They might have doubled that advantage by half-time, but Ayew headed over from another set-piece as the Bluebirds looked forlorn.
Neil Warnock's side did start the second half better, but it was past the hour mark until they tested Freddie Woodman, who saved Sean Morrison's header and then denied Gavin Whyte who shot straight at him.
Swansea were a threat on the break and Neil Etheridge needed to react sharply to deny a double effort from Dyer, while Ayew also came close, but his close-range effort was saved.
Bersant Celina forced Etheridge to smother as Cardiff threw bodies forward, but in truth Swansea always seemed in control and only a superb Morrison tackle denied Celina the chance to make it 2-0 deep into added time.
Swansea City manager Steve Cooper: "We were more than good for the result, so to do it with a performance like that is pleasing.
"I thought we did both sides of the game really well. We knew we would have to deal with a lot of long balls and aerial balls - which is fine, we have no problem with that - we did that well. When the game did settle and we were allowed to play, we were the team we want to be.
"I know how important the game is, we were representing a proud city that gets behind its football club. So the fact we can make them happy and the fans can go away happy and proud of the performance, it makes us all very, very happy.
"I felt we were in control all game. It's an easy game to lose to your emotions but I never felt under the cosh, that we were losing momentum or control of the game. We saw the game clearly, we dominated possession, created all the chances but were really hard to get through which is exactly what we want to be."
Cardiff City manager Neil Warnock: "It's disappointing to lose a derby match in the way we lost it. The goal once again is a really poor one and we've only got ourselves to blame. It gave them a a little bit of lift at a time where I thought we quietened them down - the crowd and the team. It knocked us back a little bit.
"In the second half I thought we did a lot better but our passing let us down. We had great opportunities on the breakaway and picked the wrong pass nearly all the time.
"I think the goal killed us. We didn't create enough with the opportunities we had. There were so many bad decisions in the second half I felt we shot ourselves in the foot really.
"The players have to be responsible and do what they're supposed to do. We got punished for not being on our game. We have been punished in most games, especially away from home.
"We have to defend better. We've got to learn the lessons, and we haven't so far. I just felt it was there to be won today. I know it's a derby, but I thought we quietened the crowd down. I'll be disappointed in the return match if it's not a lot louder than that."
- 5van der Hoorn
- 12DyerSubstituted forSurridgeat 74'minutes
- 22A Ayew
- 20WhyteSubstituted forMurphyat 81'minutes
- 8RallsBooked at 85mins
- 19Mendez-LaingSubstituted forPatersonat 81'minutes
- 9GlatzelSubstituted forBogleat 63'minutes
- Robert Jones
- Shots on Target
Second Half ends, Swansea City 1, Cardiff City 0.
Corner, Swansea City. Conceded by Lee Peltier.
Corner, Swansea City. Conceded by Marlon Pack.
André Ayew (Swansea City) wins a free kick on the left wing.
Foul by Marlon Pack (Cardiff City).
Corner, Swansea City. Conceded by Sean Morrison.
Attempt blocked. Bersant Celina (Swansea City) right footed shot from the left side of the box is blocked. Assisted by Wayne Routledge.
Attempt missed. Aden Flint (Cardiff City) header from the centre of the box misses to the left. Assisted by Joe Ralls with a cross.
Offside, Cardiff City. Josh Murphy tries a through ball, but Aden Flint is caught offside.
Attempt blocked. André Ayew (Swansea City) left footed shot from the centre of the box is blocked. Assisted by Sam Surridge.
Attempt blocked. Bersant Celina (Swansea City) left footed shot from outside the box is blocked.
Attempt blocked. André Ayew (Swansea City) left footed shot from outside the box is blocked. Assisted by Matt Grimes.
Attempt missed. Wayne Routledge (Swansea City) right footed shot from more than 40 yards on the left wing is too high.
Foul by George Byers (Swansea City).
Joe Ralls (Cardiff City) wins a free kick in the defensive half.
Joe Ralls (Cardiff City) is shown the yellow card for a bad foul.
Matt Grimes (Swansea City) wins a free kick in the defensive half.
Foul by Joe Ralls (Cardiff City).
Sam Surridge (Swansea City) wins a free kick in the attacking half.