Police say Denver, 24, was with his father, older brother and two other people a few blocks from the Giants' stadium after leaving the ballpark in the eighth inning of the Giants 6-4 victory when their group exchanged words with some Giants fans. The Giants fans didn't attend the game and had left a nightclub.
San Francisco police said Michael Montgomery, 21, of Lodi, was arrested on suspicion of homicide. Suhr said Montgomery made some "incriminating statements" while in custody that led to his arrest.
Another person, whose name was not released, was also taken into custody. Police said they were still looking for two more suspects.
But Montgomery's father said late Thursday that his son was jumped during the fight, and he stabbed Denver in self-defense.
Marty Montgomery told the Lodi News-Sentinel that his son said by phone that Denver, who was wearing Dodgers apparel, yelled, "Giants suck," at Montgomery's friend, who was wearing a Giants hat, when Denver and others hit his son and their friends without warning.