The media (which wants Trump to win) already setting the framing for the debate. Biden must be "vigorous" - i.e. avoid even a single misspeak or stumble - while the expectations for Trump are merely that he not spend the entire debate screaming incoherently.
Advisers to Biden are pushing him to show himself as a vigorous president at this week’s presidential debate, while advisers to Trump hope he will rein in his excesses.