Manning threw two interceptions in the first half, including one that was returned for a touchdown, and struggled in general against a dominant Seattle Seahawks defense as the Broncos slumped to a 43-8 defeat.
That took the five-time MVP to 1-2 in Super Bowls and 11-12 overall in the playoffs, but Fox has brushed off claims that his playoff record would diminish his otherwise stellar career.
"I can't really say it out loud, right here, because I get into trouble. Ludicrous would be proper English," Fox told reporters.
Manning, who is widely considered to be one of the greatest quarterbacks to have ever played the game, set new single-season records for passing yards and touchdowns in the 2013 campaign.