I have one suggestion, but this is neither particularly bold, nor is 'my' fighter particularly young. However, as he is still younger than Povetkin and only has two pro-fights under his belt, I will mention him anyway: Cuban heavyweight Odlanier Solis. He will be fighting for a legit heavyweight belt before this decade is over. Mark my words.

While Povetkin won the Amateur World Championships in Super Heavyweight in 2003 and the Olympics 2004, Solis won the Heavyweight title (as he also did in 2003). In 2005 - as Povetkin was already turning pro - Solis moved weights, and then won the WC Super Heavyweight title.

Solis defected Cuba last year, turned pro with a debut in April. Now has 2 fights under his belt - Andreas Sidon (32-7) and Alex Mazikin (10-1) - both won by 1st round knockouts. Sidon was a pretty inspired choice for a pro debut - a veteran fighter being 20-2 in his last 22 fights (only losses during this period coming against worldranked fighters Alexander Dimitrenko (WBC #6, WBA #9, WBO #3) and Taras Bidenko (WBA #7)) - which makes it all the more impressive that Solis actually stepped up in competition for his 2nd (and latest) fight. However Mazikin, with a pretty good amateur pedigree himself (2-time Olympian, silver medal at World Championships 2001 after losing the final to Ruslan Chagaev), was 10-1 with the only loss being a MD to Taras Bidenko.

Also take note of a fellow Cuban olympian: Yoan Pablo Hernandez (Cruiserweight, 22 years, 11-0). Not quite up there with Solis (or perhaps others mentioned in this thread, but definetely worth following).