By Keith Idec

Alexander Povetkin didn’t win the WBC interim heavyweight title Saturday, nor did he win many fans worldwide.

He did beat Johann Duhaupas, a last-second substitute for Bermane Stiverne. Russia’s Povetkin stopped France’s Duhaupas in the sixth round of a scheduled 10-round, non-title fight at the Ekaterinburg Expo in Ekaterinburg, Russia.

The 37-year-old Povetkin improved to 31-1 and recorded his 23rd knockout by knocking Duhaupas unconscious with a left hook just before the end of the sixth round. Duhaupas, 35, slipped to 34-4 (21 KOs).

Povetkin’s powerful punch left a retreating Duhaupas flat on his back. He lost consciousness for several seconds, but was aware of his surroundings and sitting up soon after the fight was stopped.

The Povetkin-Duhaupas bout was hastily arranged Saturday after the Voluntary Anti-Doping Agency revealed Povetkin failed another pre-fight performance-enhancing drug test.

Povetkin’s positive test prompted Stiverne to withdraw from their scheduled 12-round fight for the WBC’s interim heavyweight championship. The winner was to face WBC heavyweight champion Deontay Wilder in his following fight.

The smaller but stronger Povetkin regularly landed power shots against the plodding Duhaupas, whom Wilder knocked out in the 11th round of their June 2015 fight.

Povetkin knocked Duhaupas backward with a right hand in the third round. He later wobbled Duhaupas with a lunging left hook late in the fourth round.

An active Povetkin continued touching a sluggish Duhaupas with power punches throughout the fifth round. None of those shots appeared to affect Duhaupas as the right hand in the third round and the left hook in the fourth, though.

His fight-finishing punch caught Duhaupas flush on the right side of his face as he tried to move backward, near a corner.

As of Saturday afternoon, the WBC had not made an announcement regarding Povetkin’s second positive PED test this year.

The former WBA heavyweight champion was supposed to face Wilder in a May 21 title fight in Moscow. The WBC canceled that fight less than a week in advance because Povetkin tested positive for meldonium, a banned substance that increases blood flow and oxygen to muscles and increases stamina.

The following month, Wilder and his promoter, Lou DiBella, filed a lawsuit against Andrey Rabinsky, Povetkin’s promoter, and Povetkin. They sought more than $5 million in damages because Wilder was guaranteed a $4.36 million purse for that mandatory defense of his title.

The following week, Rabinsky and Povetkin counter-sued Wilder for at least $34.5 million for breach of contract and defamation.

Wilder made much less for stopping Chris Arreola (36-5-1, 31 KOs, 2 NC) following the eighth round of a one-sided July 16 title fight in Birmingham, Alabama. The 6-foot-7, 225-pound Wilder suffered a fractured right hand and a torn right biceps against Arreloa.

He had surgeries to repair those injuries two weeks later. The 2008 Olympian from Tuscaloosa, Alabama, returned to the gym a couple weeks ago.

He expects to return to the ring either late in February or sometime in March. Wilder was expected to box the Povetkin-Stiverne winner if he wins that tune-up bout, but that plan now will depend on the WBC’s ruling.

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