World heavyweight champion Wladimir Klitschko has had numerous close encounters with Joseph Parker's next opponent and the Ukrainian veteran believes Parker will be in for a tough night in Germany in two weeks' time.
Parker will meet the experienced Sherman Williams on the undercard of Klitschko's world title fight against Alex Leapai in Oberhausen on April 27 (NZT).
It will be the biggest test of Parker's short career, which has yielded a perfect 7-0 record, and Klitschko has sparred with Williams in the lead-up to his own bout.
Williams (36-13-2) is a durable fighter and the 1.92m Parker will have to use his superior size and quickness to look for an advantage against the Bahamian journeyman.
"I think Joseph Parker is going to face a very experienced and strong fighter in Williams," Klitschko said. "Joseph is going to have a great challenge in the ring. A very great challenge in the ring."