By Mark Eisner: Former WBA super middleweight champion Callum ‘Mundo’ Smith (28-1, 20 KOs) scored a brutal second round knockout of former world title challenger Lenin Castillo (21-4-1, 16 KOs) in his debut at light heavyweight on Saturday night at the Tottenham Hotspurs Stadium in London, England.

(Photo credit: Mark Robinson/Matchroom Boxing)

The time of the stoppage was at 55 seconds into the second round.

Smith landed a huge right hand to the head of Castillo in round two, dropping him hard on his back on the canvas. The fight was immediately halted, Castillo was badly hurt with both legs shaking in a sign of him being concussed.

For the 31-year-old Callum Smith, this was his first fight since losing his WBA 168-lb title to Canelo Alvarez last December in a one-sided fight.

Smith admitted afterward that he didn’t fight the right way against Canelo, as he spent much of the contest with his back against the ropes, covering up and not throwing much.

It was the wrong game plan to use against Canelo, and Callum paid the price in losing his WBA title.

Tonight’s performance showed that Callum has the power to compete at a high level in the light heavyweight division. Castillo went the distance in losing to WBA 175-lb champion Dmitry Bivol in a 12 round decision in 2019.

For Callum to destroy Castillo the way he did, it’s impressive, showing that he’s got the power at least to be a major power. However, there’s still a long road ahead of Smith for him before he can mix it with IBF/WBC 175-lb champion Artur Beterbiev, WBA champ Bivol, and WBO champion Joe Smith Jr.

Those guys can punch too, and they’ve got boxing ability that may prove to be a problem for Callum. The mistakes that Smith made against Canelo would get him in a lot of trouble if he makes them against Beterbiev, Bivol, and Smith Jr. Those guys have the power and the size to take Callum out if he backs up against the ropes.

In other results on the card, unbeaten welterweight prospect Florian Marku (9-0-1, 6 KOs) outboxed IBF International welterweight champion Maxim Prodan (19-1-1, 15 KOs) in beating him by a 10 round split decision. The scores were 97-93, 96-94 Marku and 99-91 Prodan.

Marku showed some good boxing skills by fighting smartly in the second half, using his jab and nice power shots to get the better of Prodan.

Undefeated Middleweight Christopher Ousley (13-0, 9 KOs) took a ten round majority decision over Khasan Baysangurov (21-2, 11 KOs) The scores were 95-95, 97-94, 97-94.