What are the most significant/notable fights which pinned 2 undefeated fighters?
Here's what I've come up with over the past few days. I know there's many more but I wanted to list the most meaningful ones. I know Chavez had several other fights, Cotto had several too as well as Holmes, Evander & Tyson but again narrowing it down to significance... Can you think of one I've missed?

Muhammad Ali 31-0 vs. Joe Fraizer 26-0
George Foreman 37-0 vs. Joe Frazier 29-0
Felix Trinidad 35-0 vs. Oscar De La Hoya 30-0
Mike Tyson 34-0 vs. Michael Spinks 31-0
Julio C. Chavez 68-0 vs. Meldrick Taylor 24-0-1
Sugar Ray Leonard 25-0 vs. Wilfred Ben...itez 38-0
Carlos Zarate 52-0 vs. Wilfredo Gomez 21-0-1
Michael Spinks 27-0 vs. Larry Holmes 45-0
Evander Holyfield 28-0 vs. Riddick Bowe 31-0
Mikkel Kessler 39-0 vs. Joe Calzaghe 43-0
Floyd Mayweather 38-0 vs. Ricky Hatton 43-0
Felix Trinidad 38-0 vs. Fernando Vargas 20-0
Donald Curry 23-0 vs. Milton McCrory 27-0-1
Joe Calzaghe 40-0 vs. Jeff Lacy 21-0
Roy Jones Jr. 26-0 vs. James Toney 44-0-2
Ricardo Lopez 47-0 & 47-0-1 vs. Rosendo Alvarez 24-0 & 24-0-1
Chris Eubank 35-0-2 vs. Graciano Rocchigiani 35-0
Carlos Zarate 45-0 vs. Alfonso Zamora 29-0
Ike Quartey 34-0-1 vs. Oscar De La Hoya 29-0
Jermain Taylor 27-0 vs. Kelly Pavlik 31-0
Vernon Forrest 33-0 vs. Sugar Shane Mosley 38-0
Felix Trinidad 23-0 vs. Yory Boy Campas 56-0
Michael Nunn 36-0 vs. James Toney 25-0-1
Julian Jackson 29-0 vs. Mike McCallum 26-0
Floyd Mayweather 24-0 vs. Diego Corrales 33-0
Donald Curry 25-0 vs. Lloyd Honeyghan 27-0
Acelino Freitas 30-0 vs. Joel Casamayor 26-0
Genaro Hernandez 32-0 vs. Oscar De La Hoya 18-0
Wilfredo Gomez 29-0-1 vs. Derrick Holmes 14-0-1
Oscar De La Hoya 22-0 vs. Miguel Angel Gonzalez 41-0
Acelino Freitas 33-0 vs. Artur Grigorian 36-0
Felix Trinidad 36-0 vs. David Reid 14-0
Austin Trout 26-0 vs. Saul Alvarez 41-0-1
Devon Alexander 21-0 vs. Timothy Bradley 27-0
Chad Dawson 22-0 vs. Tomasz Adamek 31-0
Arthur Abraham 21-0 vs. Edison Miranda 26-0
Brandon Rios 30-0 vs. Mike Alvarado 33-0
Sergey Kovalev 21-0 vs. Nathan Cleverly 26-0
Yohnny Perez 20- vs. Abner Mares 20-0
Keith Thurman 20-0 vs. Diego Chaves 22-0