Liam Smith has known Josh Kelly for years but had never thought of him as a potential opponent.

“He was always a welter. I was always a light middle,” Smith said in an interview on Flash Knockdown, a podcast from Matchroom Boxing.

They’ve remained one division apart in recent years, with Smith competing at middleweight since 2022 while Kelly moved up to the 154-pound weight class at about the same time. But the two fighters are at a point where meeting up makes sense. Smith (33-4-1, 20 KOs) is coming off a loss and needs a win to remain relevant. Kelly (15-1-1, 8 KOs) has put together five consecutive victories and needs a recognizable name on his record to help him move forward.

So they’ll meet in a middleweight bout on Sept. 21, fighting on the undercard of Anthony Joshua vs. Daniel Dubois at Wembley Stadium in London.

“Once it got offered to me, it was a no-brainer.” Smith said.  

Smith was briefly a world titleholder at junior middleweight, winning the vacant WBO belt in October 2015 with a stoppage victory over Apollo Thompson. His reign lasted for 11 months and ended with his third defense, a knockout loss to Saul "Canelo" Alvarez in September 2016. In 2018, Smith challenged Jaime Munguia for that same WBO belt, losing a unanimous decision. He also came up short on the scorecards against Magomed Kurbanov in 2021.

Smith then rattled off four straight wins, including a technical knockout of Jessie Vargas and culminating in a massive fourth-round TKO of Chris Eubank Jr. at middleweight in January 2023. The win over Eubank was tainted in the eyes of some; particularly those who saw Smith hurt his opponent with an elbow.

Eubank and Smith had a rematch last September, with Eubank getting revenge via 10th-round TKO. That was the last appearance for Smith, which means he’ll be returning to the ring after a year away.

But if Kelly and his team think Smith is vulnerable – and Smith is certain they do – then the 36-year-old Liverpudlian says they’re making a mistake.

“They might think they’re getting me at the right time,” Smith said. “It’s down to me to prove they’re not. And I fully believe that I will prove that.”

Kelly competed in the 2016 Olympics as a welterweight. He made it to the second round of the tournament and lost a decision to the eventual gold medalist, Daniyar Yeleussinov.

Kelly and his team moved somewhat ambitiously after he turned pro in 2017, though that turned out to be more to his detriment than to his benefit. In his 10th fight, Kelly faced Ray Robinson and was held to a draw in June 2019. Two fights later, in February 2021, Kelly was dropped and stopped in the sixth round by welterweight David Avanesyan. All five of Kelly’s fights since have been at 154.

“I think he’s a very good fighter,” Smith said of Kelly, a 30-year-old from Sunderland. “I think he’s a very talented fighter, a very flashy fighter. One of the fighters that’s got that natural ability, that natural flair. You can praise him. But you can also dissect him. He’s got a lot of flaws. He’s got a lot of insecurities. He lacks in many areas. He lacks in areas that I can exploit.”

Smith feels he’s got more than enough left to do “a proper number” on Kelly.

“Everyone at this level is a good fighter for six rounds. Everyone can compete,” Smith said. “But it’s the little things that make a big difference. Experience on the big stage will be one. Having to sit and bite down on your gumshield. I feel I've had to do that in many more fights than Josh. I feel he’s only had one massive, tough fight – and he didn’t really get through it.”

Follow David Greisman on Twitter @FightingWords2. His book, “Fighting Words: The Heart and Heartbreak of Boxing,” is available on Amazon.