Amir Khan, we knew already, can box. Now we also know he can fight. The distinction was drawn last night in the most important round he has ever fought here when he came out from under the pressure exerted by a Kazak brawler, Serek Yeleuov, to claim a place in Sunday's Olympic final.
For the first time in his astonishing march to national and international celebrity, the 17-year-old from Bolton was facing a serious crisis when he came out for the third round, trailing 14-16.
Yeleuov, six years Khan's senior, is no shining advert for the finer skills of the sweet science. But he has the resolution required to survive in his wild, uncharted land and also a short clubbing right that is delivered effectively, if at damaging cost to the regularity of his features. For a little while this seriously upset the young artistic fighter from Lancashire's Asian community and for some terrible moments it seemed like one of the most uplifting stories of the 28th Olympics was about to fragment.
But it didn't happen, largely because Khan refused to allow it. He outscored Yeleuov by a massive 13 points to five in the third round, which represented such an intense investigation into both Khan's technique and temperament. The challenge involved taking some considerable risk, but it was danger that was controlled by the sheer force of Khan's will and fighting momentum.
At the end of the fourth and final two-minute round, he was back in the imperious form that has alerted promoters world wide, finishing with a winning margin of 40-26 just six off the 20-point margin which brings a mandatory stoppage.
"He came out very determined and gave me a few problems early on. But I didn't lose my confidence. I always thought I could find a way to beat him," Khan said.
Stunning self-assurance from a teenager operating at Olympic level, you might think and you would be right. However, despite the stunning body of work he has assembled here, there has to be a new level of caution before the next stage of his Athenian Odyssey.
While Khan was still being hugged by British trainer Terry Edwards, his opponent tomorrow, 33-year-old Mario Kindelan was going about his ruthless work against another tough-minded member of the old Soviet empire. Kindelan, a personal favourite of Cuban president Fidel Castro after his rise to the unchallenged status of the world's best pound-for-pound amateur fighter beat the Russian Murat Khrachev by a margin of 20 points to 10. He leapt into a big early lead, then cruised his way to the final, which he said would be his final appearance in the ring.
"I've had a great time and been much honoured by country and my president," Kindelan said, "but it is time to go and I want to do it while I'm still at the top. I will be facing a good young fighter, but I think I will know too much for him. I'm the Olympic champion and the world champion, and it is the way I intend to go."
Khan, who trailed 5-7 at the end of a first round in which he seemed troubled by Yeleuov's willingness to take several punches some of them, it seemed, unnoticed by the judges in order to land one of considerable power accepts that he faces his ultimate challenge here tomorrow.
"Anything can happen when I step into the ring with Kindelan. He is a great fighter, I've watched the video and I've been in the ring with him. He beat me, but that was in May and a whole lot has happened since then. He could land a punch on me and it could be all over, but then I could land one on him. I really think anything could happen. I feel a lot more confident now then when I first fought him.
"Winning a fight like this tonight will also help me a lot. He was strong but then I was not too worried about that because I've been working on my strength a lot. I felt I could take all that he offered and then come back and see him off. I've been working particularly hard on fast starts ... and fast finishes. And in between, sometimes you have to do a lot of work. I feel this is the perfect preparation for a fight against Kindelan not in styles, but in the amount of effort and concentration I had to put in."
Khan's exultant trainer declared: "We have seen so many aspects of Amir Khan in this tournament, and tonight we saw another one and maybe the most vital one for any boxer. He showed that he can come from behind and that he was going to be intimidated by any situation he faced.
"Kindelan is a great fighter I saw him two years ago and he was superb, out of this world with his timing and his skill. But he has plateaued now and we're on the up and up."
Khan's astonishing youth and maturity has inevitability made him a star of these Olympics. In fact, there is a younger finalist, by eight days Turkey's Atagun Yalcinkaya. He beat a Russian, Sergey Kazakov, to reach his final in the light-flyweight class.
But it is Khan who is inevitably drawing the biggest spotlight. He is growing before eyes in so many different ways. Last night it was in the way of a natural-born fighter.