What did we learn from Oleksandr Usyk's knockout of Tony Bellew?

Usyk lands devastating KO vs. Bellew (0:54)

Oleksandr Usyk lands a powerful left hand that sends Tony Bellew to the canvas in the eighth round for a knockout victory. (0:54)

It didn't all go his way, but Oleksandr Usyk delivered a brutal knockout blow to end Tony Bellew's career and defend his four cruiserweight titles at the Manchester Arena on Saturday. Here are three things we learned on a big night for the Ukrainian.

Usyk shows his class, again

Usyk (16-0, 12 KOs) took his time to get control of the fight, but when he did in round six it quickly became inevitable that the champion would retain his titles.

Usyk, 31, began landing with increasing accuracy in the seventh round and Bellew (30-3-1, 20 KOs) began to unravel. Usyk had already landed a few shots flush before the telling left hand detached Bellew from his senses in the eighth round.

"I was trying to control myself in the first rounds, to control my boxing rather than just fighting," Usyk said.

Usyk kept calm and controlled, even if Bellew was winning the rounds, and waited until the opportune moment to pick his shots. He was behind on two of the scorecards at the time of the knockout, yet looked in complete control as Bellew began to fall apart.

The left hand to finish the fight, threaded through Bellew's guard, was brilliant.

Usyk heading for bigger things

What else is there for the Ukrainian to achieve at cruiserweight after six title defences? Very little. He unified all the world titles with victory over Murat Gassiev in July, and beat another rival world champion at the start of the year in Mairis Briedis.

The challenge of becoming a two-weight world champion, winning world titles at cruiserweight and heavyweight, is what now awaits Usyk.

WBA-IBF-WBO world heavyweight champion Anthony Joshua is the ultimate target, though next April -- Joshua's next fight -- is perhaps too soon.

Usyk signed a co-promotional contract with Matchroom Sport when he agreed to fight Bellew, and there are other exciting fights before Joshua, such as the winner of the fight between Dillian Whyte and Derek Chisora.

"With [Matchroom Sport promoter] Eddie Hearn we can do great things in boxing," said Alexander Krassyuk, of Usyk's co-promtoer K2 Promotions.

"Usyk would bring new spirit to the heavyweight division. He definitely needs to fight Anthony Joshua."

As WBO champion, when Usyk steps up he will move into top spot to challenge the WBO world heavyweight, who is Joshua.

It is a mouth-watering prospect, and a reality for later in 2019 or beyond.

Usyk was reserved when it came to calling on a future fight with Joshua, which suggests he will make gradual progress next year towards a title shot. "He's going to want to get his foot in and feel comfortable," Hearn said.

"You look at the people we work with, Dillian Whyte vs. Derek Chisora on December 22, then you have Alexander Povetkin, Joseph Parker, Carlos Takam, Jarrell Miller. My guess is to have a strong fight at heavyweight and go on to fight for the world heavyweight title."

Bell tolls for Bellew

Bellew can be proud of his effort, and of his career.

This was a fitting end to a career that began just over 11 years ago at Nottingham Arena, on a night when Amir Khan was the main attraction. Also on the bill that night was Kell Brook, and both Khan and Brook were ringside to see Bellew's final appearance.

Anthony Crolla was also on the bill the same night Bellew made his professional debut and the Manchester boxer enjoyed a good win on the undercard on Saturday.

But for Bellew, there are no obvious reasons for him to continue his career. He had planned to stop after beating David Haye for a second time, but when Usyk called him out Bellew could not ignore the chance to go for the undisputed world cruiserweight world title.

There is nothing left for Bellew at heavyweight: he is not interested in fighting his friend Anthony Joshua, the WBA-IBF-WBO world champion, while other fights will not be as lucrative as his recent ones.

Bellew leaves behind a career full of memorable moments; getting off the canvas to beat Ovill McKenzie in 2010, losing to Nathan Cleverly after accepting a late notice offer to challenge him for the WBO world light-heavyweight title in 2011, beating Edison Miranda, losing to Adonis Stevenson in the sixth round in a shot at the WBC world light-heavyweight title in 2013, avenging defeat to Cleverly in 2014 and stopping Ilunga Makabu in three rounds to lift the WBC world cruiserweight title in 2016 to become world champion at Goodison Park, home of his beloved Everton football club.

But perhaps the most significant wins were the two stoppage triumphs over former WBC world heavyweight champion Haye. Bellew stepped up to heavyweight and started as underdog for the fights last year and in May.

Days before he challenged Cleverly in 2011, after accepting his first world title shot at short notice, Bellew told a group of journalists: "Scousers are good at two things, fighting and telling jokes -- and I'm good at fighting," Bellew said.

He was joking of course, and we will miss Bellew's wit as well as fighting spirit.