Milo Ventimiglia warns fans of the emotional experience they are about to see in "This Is Us" Season 6. As the show is now in its final season, there will be a major event that will break everybody's heart.

After the final trailer for "This Is Us" Season 6 hints at the deteriorating health of Rebecca (Mandy Moore), this may be the major heartache Jack (Ventimiglia) will experience. However, it looks like something worse is about to happen that the actor gives a warning.

In an interview with TVLine, the 44-year-old star revealed that the final season's fourth episode is a must-watch. Though he did not give any details about it, he said that it "really hurt him personally" and gave an intriguing warning, "you've been warned."

Is this about Rebecca? In the trailer, an aged Rebecca pondered on the last thing she would remember before her memory completely declined.

By the looks of it, the final season is making viewers ready for a major death that is maybe Rebecca's. So, will fans see her demise in "This Is Us" Season 6 Episode 4 just like what Ventimiglia seems to hint at?

Meanwhile, the final season will begin with the Big Three's birthday. Just like the show's tradition, Kate (Chrizzy Metz), Randall (Sterling K. Brown) and Kevin (Justin Hartley) will be celebrating their 41st birthday this time.

Viewers will see another trilogy of episodes that focus on the Pearson sibling. There will also be an episode that will mostly center on Jack and the major death in his life.

The show's creator Dan Fogelman told People that the final season's first couple of episodes would just set everybody up for "a bit of a ride." "It's kind of like the part of the rollercoaster where you're just ticking upwards," he said.

He continued that there would be no major event at the end of the premiere episode, explaining the final season was not meant to build it up. Instead, they were preparing for the show's official ending and he knew it would take a while to build that.

With that said, it looks like fans are up for a major unexpected turn of events in "This Is Us" Season 6. With what Ventimiglia revealed, viewers should stock up on tissues as the first episode would drop on Tuesday, Jan. 4 at 9/8c on NBC.