The 29-year-old southpaw, who was appearing for the first time since he lost to Junto Nakatani last June, fought through a badly lacerated left eye, which he suffered in the second round, until the seventh round when it was deemed too bad to continue.

The fight went to the scorecards and Nishida was ahead 69-64 on all three scorecards.

"Due to the cut, I thought that I could be stopped in the middle [rounds], so I went forward and fought," Nishida (11-1, 2 KOs) told The Ring. "But I was well prepared for the fight, so I felt that I could still go [on] physically,"

The cut later required a doctor's handy work.

"The doctor was surprised that the wound was long and deep, and quite close to the eye," he said. "I heard that my eyesight may have been affected.

"The arteries were also cut and sewn together with a total of 20 stitches on the inside and outside."

Nishida and his team's bold approach in seeking out the tough Mexican has been vindicated with the IBF title eliminator win and saw him land at No. 7 in The Ring ratings, while Mercado dropped one place to No. 10.

"The decision to rise again is to become a world champion again, so I would be very happy if the next match was a world title match," he said. "In this fight I showed my desire and gained confidence that I could do it in this class by raising my level and fighting and winning against a fighter with a track record in the junior featherweight division."

Nishida's handler, Takashi Edagawa, will wait on the outcome of the winner of The Ring and undisputed champion Naoya Inoue vs. Junto Nakatani, which is tabbed to land in May.

"Nishida's next fight will be a world title match, since he won an elimination fight," said Edagawa.

"The current champion is Monster Inoue. What will happen depends on him? I don't know right now."