Vladimir Dgebuadze was stopped by Joaquin Ruiz at the 1991 Worlds

Vladimir Dgebuadze is a Georgian fighter who fought for the Soviet Union in the late 1980s through the mid-1990s. His first major international event was the 1989 European Junior Championships which he won gold. At the 1990 World Junior Championships, he won gold too.

Dgebuadze's first World Senior Championships was the 1991 World's in Barcelona. There, he was decimating the opposition and had beaten South Korea's Chung Hoon (who would eventually become 1993 World Champion) in the quarterfinal. Dgebuadze was ahead in his semifinal against Spain's Joaquin Ruiz (the current success coach), when the Spaniard's timely footsweep floored him for ippon. 

Many wondered what the outcome might have been if he, rather than Ruiz, was the one who had proceeded to the final to fight Koga. Ruiz was mainly a convenWorld Championships Barcelonational fighter. Dgebuadze, on the other hand was an extreme left-handed fighter who liked to get a belt grip on his opponent. In other words, exactly the kind of player Koga did not like to fight (in the 1988 Seoul Olympics, Koga lost to another left-handed Georgian named Tenadze, who fought exactly the same way). 

Dgebuadze did not get chosen for the 1992 Olympics, so there was no chance to meet Koga there. And they never met in any subsequent competitions. Both effectively retired in 1996. 

So, the judo world would never get to see how it would have been like if these two explosive players, with vastly contrasting styles, had met. But actually they DID meet. It was at the 1990 Kano Cup in Japan. Dgebuadze was the reigning World Junior Champion then, while Koga was the reigning World Senior Champion.