Bob Weir from the Grateful Dead collapsed during a Furthur concert last Thursday night.  But he will get by...he will survive.

Bob and Grateful Dead bassist Phil Lesh have been touring under the name Furthur for a few years now and on Thursday, they were wrapping up a nine-show residency in Port Chester, New York.

Bob was struggling throughout the night, and during "Unbroken Chain", he collapsed.  The band's crew rushed out, helped him up and sat him in a chair so he could finish the song.

But Bob left after that and didn't come back.  The band went on without him . . . telling the audience that Bob had suffered a "strained shoulder" earlier that day, while working out in the gym.

Apparently, Bob's collapse had something to do with, quote, "complications associated with medicating his shoulder."  In other words, he was just REALLY doped up?

Bob was back onstage with Further on Saturday night in Atlantic City and according to reports, he was "back in form."  (For what it's worth, Bob is 65 years old.)

Here's video of Bob collapsing.  He falls over 50 seconds in.