Wing Cuthbert, who started the first Test of the Lions' successful tour to Australia last summer, left the South African defence for dead as he ran 80 metres to touch down.
By that point though South Africa had already scored five tries themselves, Bryan Habana leading the way with a double, with Cuthbert's 68th-minute effort and James Hook's conversion making it 38-16.
That was how it would end as Willie le Roux also scored twice and Duane Vermeulen added the other try while Dan Biggar kicked two drop goals and a penalty for Wales.
And Cuthbert admitted for all the joy of his effort, as well as playing opposite hero Habana, the failure to stop South Africa meant he ultimately left the pitch in Durban bitterly disappointed.
"I can't really remember much about it. I was pretty tired by the end," Cuthbert told WalesOnline. "I just got the ball and went for it. I tried doing one of those runs in the first half, but there were a few too many of them.
"It was nice to get over the line, but it was just a shame we couldn't put an 80 minute performance in, rather than just little bits through the game.
"We had a lot of confidence going in. We thought we were going to put on a big show and get the result.
"We could have maybe had a try in the first minute. It didn't quite work out and from then they had that front-foot ball.
"They are so quick. You give them that half a yard and they just execute it. We had more line-breaks than them in the first half and we didn't take any.
"They had one or two and took everyone. That was the difference at the end of the day. Maybe the southern hemisphere sides are just a bit sharper than us at the moment.
"Every time we come down here, it seems to be that first 40 blows us away and it was a long way to get back into the game.
"But all credit to the boys, even the ones that came off the bench, they made a hell of an impact.
"We tried to claw our way back and showed a bit of promise in that last 40."