At home in their new billion-dollar stadium.
On national TV.
So 49ers owner Jed York took to Twitter to express his frustration, apologizing to fans for the performance:
Thank you #49ersfaithful for coming out strong tonight. This performance wasn't acceptable. I apologize for that
— Jed York (@JedYork) November 28, 2014
The Niners play their cross-bay rivals, the Oakland Raiders next week in a must-win game to keep up in the playoff picture while Jim Harbaugh's future hangs in the balance.
"We know what we have to do now," the 49ers head coach said right after Thursday's game. "We've got to come back and win them all. We'll set our jaw to that."
To reach the playoffs, his 7-5 team technically might not have to "win them all." But they must win three of the four games and somehow hope to gain the tiebreaking advantage over several other teams that will probably have 10 victories.
And who's apologizing?