8:20 AM PT -- Jake's rep tells TMZ the actor was not passing judgment on Jamie's performance, saying, he and Antoine "were laughing at something completely unrelated to Jamie's performance."
Jake Gyllenhaal was not impressed by Jamie Foxx's soulful rendition of the National Anthem, but at least he got in a few laughs.
Jake was sitting ringside with his "Southpaw" director Antoine Fuqua when Jamie took the mic. No doubt Jamie struggled ... he took his earpiece out immediately which is a sign of technical trouble.
Jake and Anton yukked it up and Jake checked his texts, then briefly sung along.
But props to Jamie ... he was more exciting than the fight.