Tagovailoa shared the conversation he had with his mother and father after he learned the news.
"I told my parents that I got a call from (head coach Brian Flores) and the GM was in that same room, and they told me that I was gonna be the starter," he said Wednesday. "So I told them that and, I mean, they were excited.
"They didn't believe me for a little bit. I think my dad kind of joked about it. He's like, 'After two plays, after two throws, they want to put you in now?'"
Tagovailoa made his NFL debut late in the fourth quarter of Miami's 24-0 win over the New York Jets in Week 6, completing two passes for 9 yards. He FaceTimed his parents from the field after the game.
The 22-year-old's first start will come against the Los Angeles Rams on Nov. 1, following the Dolphins' bye week.