Zhilei Zhang scored the biggest win of his career Saturday in Riyadh, Saudi Arabia, and might have effectively ended former heavyweight champion Deontay Wilder's run in the process.

China's Zhang, 41, connected with a perfectly timed counter right hook that spun Wilder in a daze. With Wilder defenseless, Zhang (27-2-1, 21 KOs) sprinted in and smashed him with another right hand that planted the American hard on the canvas.

Wilder, 38, somehow was on his feet before the count of 10, but his legs were unsteady and the referee wisely waved off the fight at 1:51 of Round 5.

"I blocked a few punches, but hell yeah, he punches hard," Zhang, speaking through an interpreter, said of Wilder (43-4-1, 42 KOs), who is regarded as one of the most powerful punchers in heavyweight history.

"I give him a lot of respect," Zhang added. "He's a heavy puncher. ... I successfully took his right hand away."

Wilder has lost four of his past five fights, including a decision defeat to Joseph Parker in December along with a pair of losses to Tyson Fury in their heavyweight championship trilogy. Wilder said before the fight that if he lost, "this could be the final goodbye, the farewell of Deontay Wilder."

Zhang, too, was reeling from a decision defeat to Parker, the former heavyweight titleholder. Zhang floored Parker twice in March but still lost on the cards.

Now, he is back on what he called the "road to the champion." That's currently Oleksandr Usyk, who defeated Fury last month in Riyadh for the undisputed championship.

Zhang closed as the -150 favorite against Wilder, according to ESPN BET. He is ESPN's No. 6 heavyweight, and Wilder entered the ring at No. 7. Zhang won a silver medal as a super heavyweight at the 2008 Olympic Games in Beijing while Wilder claimed bronze in the heavyweight division.

They appeared to be in different weight classes on Saturday, too, as Zhang outweighed Wilder by 68.2 pounds -- at 282.8 compared with Wilder's 214.6. There is no weight limit in boxing's heavyweight division.

Zhang used that size advantage to bully Wilder and smother him on the ropes. A southpaw, Zhang was able to connect with right hooks that scored time and again as Wilder cocked his vaunted right hand back but rarely let it go.

In Round 5, Zhang finally began to unload his best weapon. Wilder had just scored with a chopping right hand when he threw yet another right that was countered by Zhang for the finish.

The victory made it a clean sweep for Frank Warren's Queensberry Promotions, which was squaring off with rival U.K. promoter Eddie Hearn's Matchroom Boxing in a unique 5 vs. 5 team concept created by Turki Alalshikh, the chairman of Saudi Arabia's General Entertainment Authority.

After Zhang's TKO win, Alalshikh presented Warren with a large check worth $3 million.