Swansea City manager Steve Cooper paid tribute to Ben Wilmot as he came of age with the winner in the derby against Cardiff City.

Wilmot scored the only goal of the game as Swansea edged Cardiff in the first Welsh derby for five years at the Liberty Stadium.

The on-loan defender from Watford was only in the side because Joe Rodon has suffered an ankle injury that will require surgery and has put him out of action for club and country for months.

Wilmot struck midway through the first half with a glancing header, the 19-year-old netting his first senior goal on his full league debut for the Swans.

It was enough to settle a contest that was far more one-side than the scoreline suggests with Swansea missing a number of other chances and Cardiff struggling for any kind of fluency.

Cooper said: “First of all I’m disappointed for Joe, he picked up a fresh injury on Tuesday night,” said Cooper.

“We were a little bit worried because he had a knock on the ankle last week which he was trying to play through so we thought it was an extension of that. But it’s a new injury that’s ruled him out for a few months. He’s going to need an operation next week.

“He’s got a tendon injury that rules him out of the Wales games too. We’re disappointed for him, but what hurts him will make him stronger.

“He was close to tears. I think it hit home yesterday when he knew he wasn’t going to play. But he stood by the side of the team and didn’t leave us for one minute. That’ s disappointing for him. But we look forward to welcoming him back and looking after him through his rehab.

“For Ben, on the other side of the story, he’s a really good player and a good lad. He has had to wait for a start in the league. I know he’s played in a few League Cup games.

“He’s had to stay patient and he’s not been happy with it. We’ve had a good few conversations.

“All of the players know that we train in a way that whenever they’re called upon, we’ve made a lot of changes in the last three games, they’re ready to play. You saw that today.

“You see the fitness levels and tactical ideas it’s exactly how we want to play because we practice it every day. Ben is a good example of that.

“For him to score, I’ve got to give Mike Marsh all of the credit. The corner was right off the training ground, Marshy has a brilliant eye for spotting how to score off set plays and it’s come off today.”

The goal was enough to move Cooper’s side up to fourth in the Championship after just a second win in their last seven games – only two points behind leaders West Brom – while the visitors stay 14th.

Cardiff manager Neil Warnock said: “It’s disappointing to lose a derby match, 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 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.

“We only lost Tomlin and Hoilett only yesterday. They both pulled up in training. That was disappointing because I thought the pockets of space for Tomlin would have been what we were looking for. But we couldn’t risk them.

“I think the goal killed us. I thought you saw at the end when we went gung ho, one or two of the lads put their bodies on the line to block.

But we didn’t create enough with the opportunities we had. Mendez-Laing could have put Bogle through and Robert could have done the same. I think there were so many bad decisions in the second half we shot ourselves in the foot really.”

“We have 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 local 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.”

Despite a poor recent run, the home team started with a spring in their step in what was the 108th meeting between these two fierce rivals, deservedly taking a 24th-minute lead.

George Byers and Wayne Routledge caught their opponents out with a short-corner routine, allowing the latter time to pick out Wilmot some eight yards from goal.

The 19-year-old England U21 international did the rest with a neat glancing header into the bottom right-hand corner of the net.

Thereafter, Swansea largely controlled proceedings in the sunshine, keeping their opponents at arm’s length, while regularly threatening to double their own lead.

The closest the visitors came to giving boss Neil Warnock a point in his first South Wales derby was when Gavin Whyte was found unmarked in the box midway through the second period, only to volley straight at Swans ‘keeper Freddie Woodman.

The hosts spurned several good chances on the break, but they held firm to claim bragging rights in the first clash between these sides in five years.