Actually Valuev has fought former WBC cruiserweight champion Marcelo Dominguez who was just 5'9'' (compared to Valuev's 7'0''), who was at that time clearly past his prime and overweight. The fight was very close and competitive https://www.google.com.ua/search?q=...AUICigB&biw=1366&bih=613#imgrc=QPjnQv71ZNk8lM:
I always wondered if some iron-chinned LHW or thereabouts could take Valuev. Valuev was so slow, and the speed advantage would be so massive that I could see the smaller man avoiding everything major for 12 rounds and getting a decision. Against other HWs Valuev was still at a speed disadvantage but as the HWs weren't that fast themselves he was able to use his reach to good effect. But could the added mobility of a small guy do the trick?