Complex sentence: His first fight in the United States was supposed to be on November 12,2011 on the Manny Pacquiao vs. Juan Manuel Marquez III against an undecided opponent, but visa issues prevented Villanueva from fighting in the undercard.
Split into simpler sentences: His first fight in the United States was supposed to be on November 12,2011 on the Manny Pacquiao vs. Juan Manuel Marquez III against an undecided opponent. However, visa issues prevented Villanueva from fighting in the undercard.