The Las Vegas match-up between Kovalev and ex-super-middleweight king Ward is being billed as the fight of the year.
Kovalev is one of the most feared punchers in boxing, while American Ward is one of the most skilful.
"If Kovalev makes any mistakes I will make him pay. He can be dropped and he can be knocked out," said Ward.
"We will see who is the puncher. There have been many times when the guy who had the jackhammer did not turn out to be the puncher."
Kovalev, 33, has 30 wins and one draw from 31 professional fights, with 26 knockouts. Ward is unbeaten in 30, with 15 knockouts.
At 168lb, the 32-year-old Ward beat the likes of Denmark's Mikkel Kessler and Britain's Carl Froch and many believe him to be the world's best pound-for-pound boxer.
Kovalev beat Welshman Nathan Cleverly inside four rounds in 2013 to secure the WBO light-heavyweight title before winning the WBA and IBF belts from American legend Bernard Hopkins.
Kovalev has long been linked with a fight against WBC champion Adonis Stevenson, but the Canadian appears reluctant to share a ring with him.
"I want to destroy him [Ward]," said Kovalev, whose last fight was a scrappy points victory over the awkward Isaac Chilemba.
"It's not about who is stronger, but who is smarter, brings the best skills into the ring and is mentally stronger. If I happen to knock him out it will be a bonus for boxing fans and myself."
Andre Ward believes he can finish Sergey Kovalev early when they meet for the Russian's IBF, WBA and WBO light-heavyweight titles on Saturday.