Question: What was the title held in 2015 by Gennady Golovkin's opponent in the boxing match on HBO pay-per-view at Madison Square Garden on October 17, 2015?
Context: The King Stays King (also known as Formula, Vol.  1 Tour) is an ongoing worldwide concert tour by American singer Romeo Santos.  The tour was a promotion for his debut solo album, "Formula, Vol.  1".  On December 13, 2011, Santos announced that he would begin his initial leg of his solo tour on February 11, 2012, in the United States.  His first concert began with two consecutive shows at Madison Square Garden which became sold-out twice.  During the concert at Madison Square Garden, Santos was accompanied by fellow American bachata singer-songer Prince Royce.  For "Debate de 4", three men from the audience were randomly selected to join Santos on the song.  Usher made an appearance on the encore for the duet "Promise".  At the final concert in the Madison Square Garden, Santos was joined by American rapper P. Diddy for the song "Mi Corazoncito".  The concerts at Madison Square Garden were recorded and later released as a live album titled "" on November 6, 2012. Canelo Álvarez vs. Gennady Golovkin, billed as "Supremacy", was a professional boxing superfight contested for the unified WBA (Super), WBC, IBF, "Ring" magazine, and lineal middleweight championship.  The bout was on September 16, 2017 at T-Mobile Arena on the Las Vegas Strip.  It was televised on HBO pay-per-view in the United States, on BoxNation Box Office in the United Kingdom, and on Space in Latin America. Madison Square Garden was an indoor arena in New York City, the second by that name, and the second to be located at 26th Street and Madison Avenue in Manhattan.  Built in 1890 at the cost of a half-million dollars and closing in 1925, the arena hosted numerous events, including boxing matches, orchestral performances, light operas and romantic comedies, the annual French Ball, both the Barnum and the Ringling circuses, and the Democratic National Convention in 1924, which nominated John W. Davis after 103 ballots.  The 1890 version replaced the first Madison Square Garden, and was itself replaced by the third Madison Square Garden (which was the first to be located away from Madison Square). The Madison Square Garden Towers were the name of proposed twin 1400 ft residential skyscrapers that were to be constructed north of Madison Square Garden in Midtown Manhattan, New York City.  The project featured a complex of seven buildings, including a stadium and a new Penn Station.  The cost of the project was US$14 billion.  The architects Norman Foster and David Childs, and the architectural firm Skidmore, Owings and Merrill were designing the project.  The owners were Stephen Ross of Related Cos. and Steven Roth of Vornado Realty Trust.  The towers would have risen to be two of the tallest structures in the Midtown Manhattan skyline, with one rising higher than the Empire State Building, currently one of New York's tallest buildings at 1,250 feet (381 m) and would also have been higher than the roof, though not the spire, of One World Trade Center.  The towers are essentially canceled as Madison Square Garden is going ahead with renovations of the current arena, rather than a relocation that would have made the towers possible. Muhammad Ali and Zora Folley fought each other in a boxing match at Madison Square Garden in New York City on March 22, 1967. Ali won the bout by knocking out Folley in the seventh round.This would be Ali's last boxing match before his suspension from boxing. Cassius Clay (soon Muhammad Ali) fought Sonny Banks in a ten-round boxing match at Madison Square Garden in New York City on February 10, 1962.  Clay won the fight through a technical knockout when the referee stopped the fight in the fourth round.  The event is remembered for being the first professional boxing match in which Ali was officially knocked down in the ring by his boxing opponent. David Lemieux (born December 22, 1988) is a Canadian professional boxer who held the IBF middleweight title in 2015. Gennady Golovkin vs. Kell Brook was a professional boxing match for the unified WBC, IBF, and IBO middleweight titles.  The bout was held on September 10, 2016, at the O2 Arena in London, England.  The event was televised live on Sky Sports Box Office in the UK and HBO in the United States.  Golovkin won the fight in round 5, after Brook's corner threw in the towel. Gennady Golovkin vs David Lemieux was a boxing title fight broadcast on HBO pay-per-view at Madison Square Garden on October 17, 2015. Madison Square Garden, often called "MSG" or simply "The Garden", is a multi-purpose indoor arena in the New York City borough of Manhattan.  Located in Midtown Manhattan between 7th and 8th Avenues from 31st to 33rd Streets, it is situated atop Pennsylvania Station.  It is the fourth venue to bear the name "Madison Square Garden", the first two (1879 and 1890) of which were located on Madison Square, on East 26th Street and Madison Avenue, with the third Madison Square Garden further uptown at Eighth Avenue and 50th Street.  The Garden is used for professional basketball and ice hockey, as well as boxing, concerts, ice shows, circuses, professional wrestling and other forms of sports and entertainment.  It is close to other midtown Manhattan landmarks, including the Empire State Building, Koreatown, and Macy's at Herald Square.  It is home to the New York Rangers of the National Hockey League (NHL), the New York Knicks of the National Basketball Association (NBA), and since 1997, the New York Liberty (WNBA).
Answer: IBF middleweight title