Kal Yafai was forced to settle for a unanimous decision victory against the durable Suguru Muranaka in his first world title defence on Saturday in Birmingham.
Yafai returned to his home city as WBA super-flyweight champion but was given a thorough examination by the gutsy challenger from Japan, who showed remarkable bravery to last 12 rounds.
The title-holder Yafai, who took his belt from Luis Concepcion in December, was eventually awarded scores of 118-108 119-107 119-107 by the judges.
Yafai might have expected the early night that he was clearly seeking when, in the second round, Muranaka's knee touched the canvas. The home fighter had already scored with plenty of powerful left hooks yet Muranaka, after absorbing the straight right that floored him, continued with no ill effects.
Yafai landed two brutal left hooks in the third, each time snapping back Muranaka's head, yet the visitor remained unabated. When Muranaka then walked through a body shot that had reverberated around ringside it was clear that he was a serious threat to Yafai's championship.
The mid-way point came and went, and inconceivably the smaller and slimmer Muranaka was still taking Yafai's power. In the seventh, Yafai stung him with a straight right but he remained upright.
Yafai finally seemed to be damaging his opponent in the eighth round - a straight right, then a left hook landed flush - but the champion's momentum was halted by having a point deducted for a low blow.
The fight was becoming one-sided in Yafai's favour, yet Muranaka's steeliness wouldn't allow him to go down, although his resilience was lessening as the rounds went on.
The champion's work-rate in the final two rounds was a huge positive of his maiden defence. Eventually, even the Birmingham crowd were glad to see Muranaka go the distance.
"I had to box my way through," Yafai said. "I have a lot to work on, I am still a work in progress. He has one tough head, he took everything I had. My hands are in agony."