Anthony Ogogo has produced an inspired performance to beat reigning world champion Ievgen Khytrov.
The 23-year-old made a strong start, throwing nice combinations and finishing the first round with a right-hand counter to lead 5-3.
Khytrov moved forward in round two, making Ogogo work against the ropes and forcing the referee to give the Brit two standing counts.
Ogogo held a one-point lead going into the final round and came out firing, landing consistently and fending off a relentless late surge from the Ukrainian.
A close decision had the fighters level at 18-18 with Ogogo earning a stunning upset victory on count-back.
Ogogo now advances to the last eight and maintains a realistic chance of winning a medal in a very tough 75kg middleweight division.