LONDON -- Anthony Joshua scored a spectacular seventh-round knockout of Robert Helenius on Saturday at the O2 Arena, setting up a potential showdown next with fellow former world heavyweight champion Deontay Wilder.

Joshua (26-3, 23 KOs) produced a brilliant finish after a sluggish, tentative start in a performance that was more patient than explosive. The knockout came 1 minute, 27 seconds into Round 7.

Representatives from Saudi Arabia were in London this weekend to discuss a fight between Joshua and Wilder (43-2-1, 42 KOs) with Matchroom promoter Eddie Hearn for January.

"That's the fight we want," Hearn said in the ring afterward. "We have a three-fight plan: Robert Helenius, Deontay Wilder and [WBC champion] Tyson Fury. That's the ambition of the team.

"He's a mature heavyweight now, and against Helenius he took his time to deliver one of the knockouts of the year. He's ready now for some marquee fights. He's smarter now. He's going to take less risks."

Joshua said he would welcome a fight with Wilder next, saying the matchup would be a "win" for boxing.

"Any time's a good time to fight," Joshua said. "It's only a fight. It don't matter who it is. It could've been Wilder eight years ago or Wilder now. It is what it is at the end of the day."

He added: "There's no worry to me when it is. I'm just happy that we can get the fight going, and I think people appreciate that. I'm doing my best to keep heavyweight boxing on the map."

Helenius (32-5, 21 KOs) was a late substitute, taking the fight on a week's notice after it was announced Dillian Whyte had failed a drug test, but it was still a significant win for Joshua.

It was the English boxer's first stoppage since he knocked out Kubrat Pulev in nine rounds in December 2020, following back-to-back points defeats to Oleksandr Usyk, the WBA, IBF and WBO world champion, and a cautious unanimous points win over Jermaine Franklin in April.

After a timid start, Joshua eventually let his hands go to knock out Helenius with a thunderous right hand. It was a finish to add to his highlight reels.

Joshua, 33, seemed uninterested in matching Wilder's quick knockout of Helenius, which came in the closing seconds of the first round of their bout last October.

Helenius, 39, only agreed to fight Joshua following his third-round stoppage over Mika Mielonen in his native Finland seven days ago. He landed the first decent punch of the fight Saturday, a body shot, in the second round.

The O2 Arena was a few thousand short of capacity after the change of opponent, and those who were there began to jeer at the lack of action in the third round. Joshua seemed reluctant to throw shots, when a single right hand was his only notable punch.

Joshua, who made seven defenses in two reigns as world champion (2016 to 2019 and 2019 to 2021), threatened to launch an attack when Helenius slipped onto the ropes in the fourth round. But Helenius escaped with just a bloody nose from a short, hard jab.

Joshua started the fifth full of confidence and landed a crunching right as he began to let his punches flow more. Joshua got through with a left hook early in the fifth round, and later in the round another left hook wobbled Helenius.

But it was single shots rather than flowing combinations from Joshua, and once again the crowd began to vent their dissatisfaction in the sixth round.

Joshua responded by ending the fight in the next round with a huge right hand that caught Helenius as he was leaning back. Helenius fell flat on the canvas.

Joshua immediately jumped out of the ring to celebrate with his family and friends.

Hrgovic keeps in line for Usyk

Filip Hrgovic (16-0, 13 KOs) stayed in contention for a shot at Usyk with a 12th-round stoppage of Australian Demsey McKean.

Hrgovic, 31, from Zagreb in Croatia, hurt McKean early in the 12th with a right hook and then followed with more right hands to leave his opponent staggering across the ring after the count. Referee Marcus McDonnell abandoned the count with McKean's legs betraying him.

Hrgovic failed to shine in a close points win over Zhilei Zhang in his last fight almost a year ago, but he was sharper against McKean in an eliminator for the IBF world title held by Usyk, the Ukrainian who defends his belts versus Englishman Daniel Dubois in Wroclaw, Poland, on Aug. 26.

Hrgovic landed a better selection and quantity of punches, among them a great right-left combination in the second round.

McKean (22-1, 14 KOs), a southpaw from Queensland who trains in Essex, England, landed a flurry of punches early in the fifth round, but later in the round he was rocked onto his heals by a stiff right hand.

Hrgovic hurt McKean, 32, in the ninth round with a big right hand to the head. McKean, who was brave throughout a spirited performance, was forced to hold on to avoid further damage and a count.

But Hrgovic caught up with McKean again in the last round with a short right hook to the jaw. Hrgovic followed with a series of clubbing right hooks to the head, and when referee Marcus McDonnell started the count, McKean stumbled across the ring. McDonnell waved off the fight.

Bloodied Chisora outpoints Washington

Also on the undercard, 39-year-old Derek Chisora earned a unanimous decision over Gerald Washington in a close 10-round bout.

Chisora (34-12, 23 KOs) had to contend with a nasty cut by his right eye from early in the fight, but his aggression was enough to see him win by scores of 98-93, 97-94 and 96-94.

After being stopped in 10 rounds by Fury in December 2022, Saturday's win puts Chisora in line possibly for a fight on the undercard of Joshua-Wilder in Saudi Arabia.

Chisora, who has lived in north London since he moved from Zimbabwe in childhood, has won as many as he has lost in recent years, and despite being slower than he was, his relentless aggression still produces good results like this one.

Washington (20-6-1, 13 KOs), from California, has now lost four of his past five fights but he produced some good moments.

Chisora, who walked to the ring with his two young daughters, was quickly on the front foot and a right hand briefly unsteadied Washington in the first round.

But Chisora was left bleeding from a cut around the right eye caused by a clash of heads early in the second round and, as the blood began to flow, he was caught by an uppercut.

Washington, 41, who lasted five rounds against Wilder for the WBC world title in 2017, began to find more opportunities to land in the third round as Chisora's work became ragged.

Chisora absorbed a straight left in the fourth round as Washington picked counter shots, but Chisora responded with a big fifth round. Chisora's aggression got him back in the fight, and in the sixth he caught Washington with a big right hand.

But Washington finished the seventh on top, when he landed a left while on the ropes before the fight swung back to Chisora in the later rounds.