Rey Mysterio entered the Royal Rumble match at #25 at the namesake event but was eliminated by Orton. Mysterio failed to win the United States Championship at Fastlane in a fatal-4-way where Samoa Joe retained in a match also involving R-Truth and Andrade.
On the March 12 edition of SmackDown Live, Mysterio pinned Joe in a tag team match which led to Mysterio earning a United States Championship opportunity against Joe at WrestleMania 35 where he was defeated by Joe. During the 2019 WWE Superstar Shake-up, Mysterio was drafted to Raw.
At Money in the Bank on May 19, Mysterio defeated Joe to win his first United States Championship, becoming the twenty-first WWE Grand Slam Champion in the process. Two weeks later on Raw, Mysterio announced that he would vacate the title the week after due to suffering an injury from a post-match beatdown by Joe.
Mysterio returned on July 8's edition of Raw and issued an open challenge which was accepted by Bobby Lashley where he was defeated by him and also suffered a post-match assault from Lashley. In August, Mysterio teased his retirement due to multiple losses and amounting injuries, with his son trying to persuade him to not give up.
In a recent interview with Newsweek, Mysterio revealed what advice he gave Dominick: “The number one advice I give him, and I’ll remind him to this day if I have to, you cannot live in my shadow. You can’t.
You’re a much bigger person. He’s 6’1″ and about 200 pounds so you cannot even compare my in-ring ability to his. You have to be yourself. You have to create your own legacy. You can’t follow in my footsteps.
Yes, you are my son, but you have to do your own thing. Don’t ever go back and try to be me. I think he picked that up on day one. He definitely created his own legacy and creating his own mold. I think the hardest thing for the fans trying to compare him to what I did in my career.
There’s not going to be another Rey Mysterio. There never will be — just like there will never be another Shawn Michaels or Eddie Guerrero or Undertaker — there’s only one. For my son, that’s gotta be him he’s gotta create his own style and his own legacy”.