Ireland's Katie Taylor beat Christina Linardatou by a unanimous points decision to claim the WBO super-lightweight title in Manchester.
Following the hard-earned victory, the 33-year-old becomes a two-weight champion, already holding the lightweight crown.
Taylor's last contest ended with a split-decision win over Delfine Persoon in New York, which saw her unify the entire division with the WBO, WBA, WBC and IBF titles.
Following a cagey opening to Saturday's 10-round showdown against the Greece-based Dominican Republic fighter, Bray boxer Taylor slowly upped the tempo.
The Irishwoman, though, was also on the end of some big shots, which saw her right eye swell and was also caught by a left hook early in the fifth round.
As the fight entered the latter stages, Taylor had to respond again following another powerful left from her 31-year-old opponent.
The 2012 Olympic lightweight champion regrouped for the closing stages, landing a big punch in the final round which removed Linardatou's gumshield and ignited the crowd.
With neither fighter able to produce a finish, the result went to the judges' scorecards, which fell in Taylor's favour 96-94, 97-93 and 97-93.
Taylor, whose record now stands at 15-0, felt she had boxed clever to fend off Linardatou's challenge.
"I'm making history again, breaking boundaries again and I'm a two-weight world champion and there's still more to come," Taylor said afterwards to Sky Sports.
"I thought I boxed beautifully on the outside and I didn't get sucked into a fight."
Later on Saturday's fight card, Anthony Crolla took a majority decision over Frank Urguiaga to claim the vacant WBA continental lightweight title in what was his final contest.
The 32-year-old Manchester boxer secured a 95-95, 98-92, 97-93 victory on the judges' score to deliver a memorable send-off to his 45-fight career which saw him hold the WBA lightweight title.
"Getting the win was the main thing, but now I know my time's up. It was always going to be my last fight but I know it's the right decision," Crolla told BBC Radio 5 Live Sports Extra.
"Hopefully I've left a bit of a legacy. I will be back in the gym training the youngsters and hopefully some of the champions of the future."
