An 18-game unbeaten run came to an end at the Liberty Stadium, where Alfie Mawson’s strike five minutes before the interval was the difference between the sides.
The Reds threatened more in the second period – and Roberto Firmino sent a header against the post in the final seconds – but it was not enough in Wales.
“That’s how we wanted to play in the first half also, only we didn’t,” Wijnaldum told Liverpoolfc.com post-match.
“We’re more disappointed because we gave one half away, we gave them their only chance and they scored a goal. If you play the whole game like we played the second half you would be disappointed but at least you tried.