Alexander Povetkin did just enough to earn a points decision over Marco Huck to retain his WBA heavyweight title on Saturday.
Huck, the WBO cruiserweight champion, had the undefeated 32-year-old Povetkin staggering back against the ropes in the fourth and seventh rounds, but the German was unable to deliver the telling blow.
Belgian judge Philippe Verbeke called it a draw, 114-114, but England's John Coyle and South Africa's Stanley Christodoulou awarded it 116-113 and 116-112 respectively to the defending champion.
The decision was greeted by a chorus of boos at Porsche Arena, as Huck claimed victory over his nine-kilogram(20-pound)-heavier opponent.
''He couldn't stand anymore and he's been judged champion,'' Huck said. ''The guy couldn't stand.''
Povetkin was standing after making his second defense of the title, but appeared exhausted after an engaging bout.
''I underestimated him,'' said Povetkin, who improved his record to 23-0 (16 KOs). ''Perhaps I didn't take this fight seriously enough.''
The Russian started well, but the bout came to life in the fourth, when he seemed in serious trouble as the Yugoslav-born Huck launched combination blows.
Huck's best chance of finishing the bout early came in the seventh, when Povetkin was saved only by the bell. He managed to compose himself for the remaining rounds.
Both fighters found it hard to land clean blows, though Huck caught Povetkin with a huge right in the 10th round and again in the 12th, after Povetkin opened a gash above Huck's right eye.
''A lot of people who saw this fight see me as the winner,'' said the 27-year-old Huck, who dropped to 34-2 (25 KOs).
Povetkin earned the title by defeating Ruslan Chagaev last August. It had been Wladimir Klitschko's, but the WBA vacated the title when it elevated the Ukrainian to ''super champion'' after his victory over David Haye the month before.
