Michael Strahan's game-worn Super Bowl 42 jersey -- when his NY Giants upset Tom Brady's UNDEFEATED Patriots in 2008 -- just hit the auction block ... and it's expected to crack the $100k mark!
TMZ Sports has learned ... Goldin Auctions is featuring Strahan's white and red NYG jersey in a current auction. The starting bid was $20k and it quickly exploded to $36k.
The game -- played on February 3, 2008 in Glendale, AZ -- is widely considered one of the best in Super Bowl history.