By Keith Idec

NEW YORK — The last time Darren Barker came from England to the United States to fight for a middleweight title, he wasn’t even certain he could compete at boxing’s elite level.

Barker was undefeated before he fought Sergio Martinez in October 2011, but his 23-0 record had been built against an unremarkable group of opponents almost exclusively in Great Britain. It wasn’t until the previously untested contender’s strong showing against the heavily favored southpaw from Argentina that Barker began believing he is a championship-caliber fighter.

The London resident thinks the considerable confidence boost he got from that 11th-round knockout defeat will help him defeat Daniel Geale and leave Revel in Atlantic City with a middleweight title Saturday night.

Handicappers have installed the 31-year-old Barker (25-1, 16 KOs) as a slight underdog entering a 12-round fight for Geale’s IBF middleweight championship, the main event of an HBO “Boxing After Dark” tripleheader scheduled to start at 9:45 p.m ET/PT. The odds aside, Barker considers the experience he gained against Martinez (51-2-2, 28 KOs), even though he lost, to be more valuable than anything Australia’s Geale (29-1, 15 KOs) has accomplished during his nine-year pro career.

“One thing I took from the Martinez fight is lot of belief,” said Barker, who was behind on all three scorecards (99-91, 97-94, 96-94) when the Martinez match was stopped. “I don’t think I had bundles of it before. I’ve always had the ability, but you can never gauge how good of a fighter you are. But coming up against one of the pound-for-pound greats, one of the middleweight greats, it proved to myself that I belong on the world stage and that I can win a world title.

“A lot of people think I’m taking Daniel Geale lightly. That’s not the case at all. He’s a good fighter. They don’t hand out genuine world titles for nothing. It’s just I believe I’m stronger in each department. I think I hit harder, I’m quicker, I’m stronger, and it’s about me getting it right on the night. If I do, I’ll definitely be the new IBF middleweight champion of the world.”

The 32-year-old Geale also was impressed with the way Barker boxed Martinez, who was a top-five fighter on most mythical pound-for-pound lists when he battled Barker at Boardwalk Hall in Atlantic City.

“I thought he did really well [against Martinez],” Geale said. “I thought he did enough to frustrate Sergio at times. It’s just Sergio’s power shone through at the end. But he put on a good performance and he proved that he’s got a great skill base.”

Although Martinez is left-handed, the right-handed Geale learned plenty about Barker from watching footage of that fight, which HBO also televised.

“I thought he out-boxed Sergio in phases, sort of was picking him off,” said Geale, who’ll make the fifth defense of a title he won from Germany’s Sebastian Sylvester (34-5-1, 16 KOs) in May 2011. “I see him doing similar things to myself. He’ll try and pot-shot me, he’ll try and use his reach and be evasive as well. I’m not going to let that happen.”

Keith Idec covers boxing for The Record and Herald News, of Woodland Park, N.J., and BoxingScene.com. He can be reached on Twitter @Idecboxing.