Anthony Joshua believes he can overcome Charles Martin's southpaw stance after dedicating much of the build-up to Saturday's fight to that aim.
The Olympic gold medallist, 26, challenges IBF heavyweight champion Martin in only his 16th fight as a professional and having not faced a southpaw since leaving the amateur ranks.
It was there that one his three defeats, and the only one via stoppage, came against Romanian southpaw Mihai Nistor, and where he similarly struggled to overcome Roberto Cammarelle in the 2012 Olympics final.
Long-term rival Dillian Whyte also seriously threatened him with a left hook when they fought in December and said afterwards he could see that that defensive weakness remains. However, having extensively worked with southpaw sparring partners since then, Joshua is confident it has been overcome.
"Early on I was getting hit with the backhand a bit," Joshua said. "I was thinking, 'This is a bit tricky', but now I'm defending it, slipping it and countering, 'Bang, bang'. That's what's helped me develop, having sparring partners over for the whole duration.
"You just have to switch on to certain shots. They are no different, but you just are unaware to certain shots. Now I am switched on to big hooks coming round.
"At first, it was aching my (left) arm a lot keeping it (tight), but my (upper arm) muscles have developed a lot more. I have to keep it up, counter. I'm happy with the progression over the last eight weeks.
"I had three southpaws over and I was getting a few rounds in with orthodox fighters just steaming forward, going toe-to-toe.
"Sparring is key. Bag work is bag work, pad work is important, but sparring is the key. I have been blessed to have three sparring partners over for the last six weeks. My last rounds of sparring were on Tuesday. That's been the key to learning how to deal with southpaws."
It has been pointed out that compatriot David Price, once almost as highly rated as Joshua, lost his undefeated status against awkward American southpaw Tony Thompson in 2013.
As Price similarly experienced, Joshua has spent much of the past week exchanging insults with WBA and WBO champion Tyson Fury, whom Martin considers superior to Joshua.
"He's not better than Fury because Fury can box," said the undefeated American, 29. "Fury can move, he can keep it low (fighting at range), he can keep it so low you can't get to him."