Zhang Zhilei got in some much-needed rounds Saturday against an opponent who’s never been stopped.

The huge Chinese southpaw soundly defeated Andriy Rudenko by unanimous decision in a 10-round heavyweight fight at Casino de Monte Carlo in Monte Carlo. The 36-year-old Zhilei comfortably beat Rudenko on all three scorecards (99-91, 98-92, 97-93) to remain unbeaten.

The 6-feet-6, 278-pound Zhilei (21-0, 16 KOs) buzzed Rudenko with a straight left hand with just over a minute to go in the third round, but he couldn’t finish off the durable Ukrainian veteran.

Zhilei, who fought for the first time in 14 months, landed an array of power punches and kept Rudenko on his back foot during a dominant fifth round. Rudenko was offensive enough to keep Zhilei honest for much of the second half of their bout, but Zhilei landed hard shots that affected Rudenko in the final two rounds.

Zhilei, a 2008 Olympic silver medalist, drilled Rudenko with a straight left hand around the midway mark of the ninth round. He also wobbled Rudenko by landing a right hook with just under two minutes to go in the 10th and final round.

Rudenko survived to the final bell, but he didn’t do much overall to test Zhilei, who went past the sixth round for the first time in his five-year pro career.

Zhilei had cracked the WBO’s top 15 prior to this lengthy layoff.

He remained out of the ring for so long due in large part to visa issues that kept him out of the U.S. for nearly a year. Zhilei lives in northern New Jersey when he trains for fights.

The 36-year-old Rudenko (32-5, 20 KOs) took this fight on barely one week’s notice, once Sergey Kuzmin pulled out of it. Kuzmin (15-1, 11 KOs) would’ve represented a step up in competition for Zhilei, but he suffered a foot injury that forced him to withdraw from their fight last week.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.