Robert Helenius replaces Dillian Whyte as Anthony Joshua’s opponent for Saturday

Joshua was set to face fellow British heavyweight Whyte, but the bout had to be cancelled last weekend after “adverse analytical findings” were detected in a doping test conducted by Whyte, who has vowed to clear his name.

It left Matchroom in a race against time to find a new opponent but, 72 hours after Whyte’s failed test was made public, 39-year-old Helenius has answered the SOS from the promotion company despite having fought in Finland last weekend.

Former two-time world heavyweight champion Joshua said: “This wasn’t in the script.

“I respect Helenius and, may I say, I respect any male or female who steps into the ring.

“I am laser-focused on the win. I can make steps forward to bigger and better things but the road map has a check point – Saturday night. May the best man win.”

Helenius said: “I am excited about fighting Anthony Joshua on August 12.

“I am a true Viking that is willing to face any challenge at a moment’s notice. This is not an opportunity I was going to let slip away. I plan to make the most of it!”

Stockholm-born Helenius (32-4, 21KOs) is no stranger to the British boxing scene after he beat Derek Chisora in a contentious split decision to win the vacant European Championship title in 2011.

The heavyweight with an orthodox style lost to Whyte on points six years later in Cardiff but only after he took the bout at two weeks notice.

Whyte’s failed test saw Matchroom immediately cancel the planned domestic clash and opened the door for Helenius to secure another handsome payday in Britain.

This will be the 37th fight of the veteran’s career, but he has only fought three times since the coronavirus pandemic started in 2020.

An added element of intrigue to this clash with Joshua (25-3, 22KOs) is the fact Helenius was knocked out in the first round by former world heavyweight champion Deontay Wilder in Brooklyn last October.

With talks still ongoing around Wilder and Joshua potentially fighting each other later this year, all eyes will be on how the Briton performs against his 39-year-old opponent.

Helenius will also enter this bout off the back of his 32nd victory after he was able to stop Mika Mielonen in the third round of their contest in Finland last Saturday.

Matchroom has confirmed the original undercard, which contains Chisora, will remain the same, but Saturday will no longer be a pay-per-view fight and instead be accessible for DAZN customers with an existing subscription.

“To get the news on Saturday was really disappointing, not only for us but for Anthony Joshua and for the fans,” Matchroom Sport chairman Eddie Hearn added.

“But we got to work and we have done what we’re good at – and we have managed to keep the show on.

“AJ has been unbelievable throughout this whole process. He is someone who is ready to fight having trained for 12 weeks in Dallas with Derrick James. He has always been a great pro but this just shows me again the hunger he has for the sport.

“He wants to go out there this Saturday in front of a sold-out crowd at The O2 and perform.

“There were a lot of options. But we had to make sure it was the right fight for the right deal. I think Robert Helenius is a good fight.

“Yes, he lost to Deontay Wilder but that was by a shot that would have probably knocked out a horse! But he came to fight. He can really punch, he’s 6ft 8in and he won at the weekend.

“Ultimately there is criticism in whatever you do, but I actually think this is a tricky and dangerous fight.”

Tickets will remain valid for all existing ticketholders, but refunds will be available for ticketholders.