Wales back-rower Ellis Jenkins suffers worrying knee injury
Ellis Jenkins suffered suspected ruptured knee ligaments in the last moments of Wales' historic 20-11 win over South Africa.
The Cardiff Blues captain was named man of the match for his back-row efforts as Wales completed their first autumn clean sweep.
Coach Warren Gatland said Jenkins' injury "looks like an ACL [anterior cruciate ligament]".
Jenkins will have a scan on the injury on Monday.
"It is not brilliant and he is obviously very disappointed," said Gatland.
"I thought his performance was outstanding and he deserved man of the match.
"At the moment you have to feel for him and hopefully it is not too bad. We can rehab him and get him back on the field as soon as we possibly can."
It could be a bitter blow for Jenkins before the 2019 Six Nations and the World Cup, which starts in Japan next September.
Jenkins had only been named as a replacement on Thursday before being drafted in to start for elbow injury victim Dan Lydiate.
He then switched from blind-side to number eight when Ross Moriarty failed a head injury assessment in the first half.
In an outstanding performance, Jenkins set up Wales' opening try for prop Tomas Francis and helped fellow back-rower Justin Tipuric exert a telling influence on the outcome.
But Ellis' game ended on a stretcher, with him being consoled by team-mates whose celebrations were muted by his predicament.
Wales' 'toughest' autumn Test
Following wins against Scotland, Australia and Tonga, Gatland said the Springboks proved to be his side's hardest test this autumn.
Wales led 14-3 at half-time following tries for prop Francis and full-back Liam Williams.
South Africa responded with a try from centre Jessie Kriel before Dan Biggar came off the bench to kick two late penalties.
It was a ninth successive Wales win, their longest winning streak since 1999.
"It was the toughest game we had played in the autumn, and there were aspects we need to take away and challenge the players to be hard on themselves technically," Gatland said.
"When they go back to play with their regions they get away with things.
"But against the top teams there are a few things technically we have to work on, which are exposed against the best teams in the world.
"The scrum was under a bit of pressure and there is some game management to improve, but we have been able to keep our composure."
'Finish on a high'
Gatland is now looking forward to the 2019 Six Nations and World Cup that follows in Japan, after which his Wales reign will end.
"We are in a good place, but we know there is a lot of work to do if we want to have a good World Cup," said Gatland.
"We keep our head down and start thinking about the Six Nations, which will hopefully be good.
"It's my last 12 months and I would like to finish it on a high, help players finish as well as we possibly can and leave Welsh rugby in a good position.
"We have got a special group of players who the Welsh public should be really proud of.
"The way they have conducted themselves on and off the field and how they have prepared in this campaign has been outstanding."