Finnish heavyweight Robert Helenius overcame a close call in the sixth round on the way to a lackluster unanimous-decision victory over journeyman Sherman “Tank” Williams, of Vero Beach, Fla., in Saturday’s EPIX-televised bout from the Ice Hall in Helsinki.

Although the 28-year-old Helenius (18-0, 11 knockouts) won, 98-93, 99-93, and, 99-91, he had to survive a treacherous sixth round, during which the 40-year-old Williams (39-12-2, 19 KOs) wobbled him with a head-swiveling overhand right.

Nicknamed The “Nordic Nightmare,” the 6-foot-6 1/2 Helenius weighed 249.3 pounds compared to the career-high 264.8 for the 5-11 Williams.

Helenius was coming off a split-decision victory over Dereck Chisora in December.

Lem Satterfield can be reached at [email protected]