Shannon Sharpe Skipped FS1 Show Over Skip Bayless' Damar Hamlin Tweet

Skip Bayless hosted Tuesday morning's episode of 'Undisputed' alone, without Shannon Sharpe, and it was no accident ... we're told the Hall of Famer was upset with the opinionated TV host's controversial tweet sent minutes after Damar Hamlin's heart stopped during MNF.

And, TMZ Sports is told the network -- which wants Sharpe back as soon as possible -- doesn't know if he will return to work on Wednesday.

The controversy started when Bayless tweeted ... "No doubt the NFL is considering postponing the rest of this game - but how? This late in the season, a game of this magnitude is crucial to the regular-season outcome ... which suddenly seems so irrelevant."

The backlash came fast and furiously ... with everyone from fans to current and former star athletes like Darrelle Revis, Dez Bryant, "Sauce" Gardner and others going in on Skip.

In the wake of criticism, and less than an hour after his original message, Bayless attempted to clarify his point, writing ... "Nothing is more important than that young man's health. That was the point of my last tweet. I'm sorry if that was misunderstood but his health is all that matters. Again, everything else is irrelevant. I prayed for him & will continue to."

But, clearly, it wasn't enough for his partner, Shannon ... 'cause when 'Undisputed' went live Tuesday morning, Sharpe was nowhere to be found.

Some speculated Shannon could've simply had the day off, but our sources tell us that's not the case -- this was a direct reaction to Bayless' tweet.

A few minutes into the show, Skip seemingly tried to clear the air without directly addressing the reason behind Shannon's absence, saying, "Obviously, my partner, Shannon Sharpe, is not here today. I look forward to seeing him tomorrow."

Bayless also started the show telling the audience he was going to (attempt to) approach the show as he would any other weekday ... though he wasn't sure if he'd be able to get through the emotional topic.

"I apologize for what we've set out to do if it offends anyone because we're going to try to do the show pretty much as we usually do the show but I'll admit upfront, I'm still shook up by what happened last night to Damar Hamlin."

Skip continued ... "In fact, I'm still wrecked. In fact, I'm not sure I'm capable of doing this show today but after barely sleeping on it, I decided to give it a try. Maybe I'll fail, maybe we will fail but we're going to try."