Ricky Burns was left admiring the power of Kiryl Relikh after a thrilling win over the hardy Belarusian at Glasgow's SSE Hydro Arena on Friday night.
It was the Coatbridge fighter's first defence of his WBA world super-lightweight title, and he was made to work for the victory.
Relikh, under the guidance of former world champion Ricky Hatton, had arrived with a record of 19 knockouts in 21 wins, and he demonstrated to Burns just why he held such an impressive record.
The 33-year-old struggled at times to get on top of the challenger during a pulsating battle but ultimately came through on the judges' scorecards, 118-110 116-112 116-112.
Afterwards he said: "I feel sore. I have been in with big punchers before and the sparring and fights I have been in are always tough going, but that boy could bang.
"In the second round he caught me with a couple and I had to grit the teeth because he hurt me. Throughout the fight I stuck with what Tony (Sims, trainer) and I had been working on.
"We knew he was flat-footed and would look to try for the big hooks all the time but he could bang.
"He took a couple of right hands and a couple of body shots but his poker face was just as good as mine. He seemed to grit the teeth as well, which is good.
"He will definitely come again. I said before the fight that we expected a hard 12 rounds and we always prepare for that.
"And the way I trained for the fight, I think I brought most of that into the ring, which is good."
The atmosphere was electric as Burns entered the ring, but the relatively unknown challenger started with some confidence.
Relikh, who made the 10-stone weight only at the third attempt, quietened the crowd in round one by forcing the pace and finding his way through the guard.
Three-weight world champion Burns, who won the belt in May by knocking out Michele Di Rocco in the same arena in eight rounds, had to fight mostly off the back foot in the early stages.
Slick-moving Relikh kept coming forward while avoiding most of Burns' attempts to counter.
A straight right by Burns near the end of the fourth got the crowd cheering again and he was looking better in the next round when he found the target more often.
The fans found their voice again as Burns put some combinations together but Relikh shrugged them off and again had his man back-pedalling.
It was turning into a difficult night for the Scot, who was having to tap into his vast experience.
Relikh kept stalking but two stunning rights by Burns in the eighth appeared to sow some seeds of doubt in the younger man's mind.
The snap had left Relikh's punches, with the spring appearing to leave his legs and the champion began to impose himself.
The 26-year-old, however, came back in the 10th with renewed vigour, scoring with a big right and a big left.
The men swapped punches in the 12th - the home fighter went to the ground but it was due to a slip - before the final bell signalled a successful defence which owed much to Burns' resilience.