Eddie Jones is delighted that his "gamble" on Nick Isiekwe has paid off, as the England lock prepares to make his first Test start in place of Joe Launchbury.
Launchbury's absence with a calf injury has caused some concern, but head coach Jones is supremely confident about the talent of Isiekwe, someone he considered "a project player" just a year ago.
Jones has watched the 20-year-old go from strength to strength since stepping into the England fold for last year's tour of Argentina.
And having won the Premiership title with Saracens, Jones is convinced Isiekwe is the obvious option for England against South Africa, with Launchbury out for Saturday's opener.
"I've been hugely impressed with the kid. We took a bit of a gamble on him last year and took him as a project player," the England coach told a news conference.
"[Isiekwe] came back from that tour and secured a starting spot with Saracens, playing lock and number six. As the season went on, he kept getting more and more impressive in doing the simple things well.
"He's come into the squad on the back of Saracens' Premiership [win] a different lad. He's confident about what he's good at. He's a great athlete, an incredible athlete for a big guy, and he adds speed to the pack."
Jonny Hill was another option for Jones, but the coach feels Isiekwe is in pole position to deputise for Wasps star Launchbury.
"[Isiekwe] has got the ability to not only be a good line-out forward but to be a very good contributor around the field," he said.
"Jonny Hill's unlucky. He's impressed us as well. We've only had a short period of time with him. He's a tough, no-nonsense type lock.
"He needs to do a bit of work on certain areas of his game but he, like a number of the other 11 players that missed out on the 23, can feel a bit aggrieved."