Coach Rassie Erasmus says the South Africa team he called "terrible" after they lost to England this weekend can go on to win the 2019 Rugby World Cup in Japan.
The Springboks crumbled 25-10 to the Red Rose in a dead-rubber final Test having already clinched the series with victories in Johannesburg and Bloemfontein.
England adapted much better to a rain-soaked Newlands stadium pitch in Cape Town and were less error-prone than South Africa, whose fly-half Elton Jantjies performed poorly.
"We were terrible today (Saturday) in my opinion," said former Springboks flanker and skipper Erasmus, who succeeded sacked Allister Coetzee this year.
"However, I really think we can win the World Cup. If we get things right quickly, then we are definitely in with a chance.
"There is a lot of things we have got to balance so that we have a fresh experienced team with a lot of talent when we go to the World Cup."
South Africa are in Pool B with defending champions New Zealand, Italy, Africa 1 (probably Namibia) and the winners of an inter-continent repechage tournament.
Australia-born Eddie Jones, coach of the England team who snapped a six-match losing streak by winning in Cape Town, backs the optimism of Erasmus.
"South Africa have got some bloody good young players and incredible depth," said Jones, an assistant coach of the 2007 World Cup-winning Springboks.
"They have made some really good gains and will continue to get stronger as the World Cup approaches.
"The big difference between the Springboks of today and six months ago is that they work much harder off the ball.
"They have got a strong maul and when the opportunity arises, have the ability to move the ball wide. In full-back Willie le Roux they have someone who makes really good decisions.
"The South African side is revitalised, they are well coached, well balanced and played some good rugby during the series against us.
"In the first two games they were too good for us and deserved to win the series, but there were small margins in all three Tests."
England and South Africa meet again at Twickenham in London during November when the Springboks tour Europe.
Before that, South Africa face Argentina, Australia and New Zealand home and away in the Rugby Championship between August and October.
They will do so without number eight Duane Vermeulen, who capped an impressive series by winning the second Test man-of-the-match award.
"I am not available -- that is all I can say‚" said Vermeulen, who is reportedly joining a Japanese club.
The silver lining is that another number eight, 2017 Springboks skipper Warren Whiteley, should be available after missing the England series through injury.