Carl Froch likened hitting Glen Johnson to punching an "oak tree" following his majority decision victory in Atlantic City.
Froch retained his WBC super-middleweight title - and progressed to the final of the Super Six Series - after overcoming Johnson in a thrilling encounter at the Broadwalk Hall.
The Cobra was eventually awarded the fight 114-114, 116-112 and 117-111 having had to overcome some anxious moments.
The wily 42-year-old veteran Johnson, who has been in with some of the best light-heavyweights in the world, made life tough for Froch and landed some huge rights
Froch, though, responded with some big shots and telling combinations of his own - with the 33-year-old praising Johnson at the end.
Froch said: "He's very tough, very strong and durable.
"I hit him with some great shots but it's like sparring an oak tree, if you can imagine that.
"You don't feel like the shots hurt so you stop throwing the hard, hurtful shots and start picking your punches and getting through the round.
"I was in my comfort zone and steady but it's hard to get out of that comfort zone then.
"I stepped it up towards the end to make sure I won but I don't know what the 114-114 scores was from Japan judge. That's a bad score, the 117-111 was more like it."
Froch hailed the power of Johnson, but insists that despite being caught with some hard-looking rights, he was never troubled.
He added: "Johnson hit me with a couple of right hands but they didn't bother me. They caught me off balance, to be fair.
"You feel it, but I'm known for having a strong chin."
Johnson admitted Froch edged it, and said: "I felt I was in it and when it's close like that you really don't know (how it will go).
"My corner was telling me to pick it up as I was falling behind, so I was trying to pick it up. But he tried to take me out my gameplan."