PGA Champ Jason Dufner -- Tiger Woods Won't Let Me Watch Auburn Game!!!

Gotta love Jason Dufner's honesty -- 'cause the PGA champ tells TMZ Sports the fact he'll be golfing with Tiger Woods Saturday instead of watching Auburn play for the SEC Championship is totally "gonna suck."

Dufner hit us with the straight talk on his way out of LAX yesterday ... when we asked about his unsuccessful attempt to persuade Tiger to change the tourney he's hosting this weekend so Jason could watch his Alma Mater take on Missouri.

In case you missed it ... Dufner -- who's slated to play in Tiger's World Challenge in Thousand Oaks, CA this weekend -- tweeted out to Woods on Monday begging Tiger to allow him to play all of his rounds on Thursday and Friday so he could be free to watch the game on Sat.

Tiger shot those plans down.

Dufner's reaction -- "It's gonna suck not being able to watch my guys play."

FYI -- Tiger's sort of in the same boat ... since his Alma Mater, Stanford, is set to take on Arizona State for the Pac 12 Championship on the very same day.