"I'm looking forward to pitching my game and [playing] some baseball," Roth said.
Scioscia opted to go with Roth because he feels it gives the bullpen better options.
"It's going to be a staff day, unless Michael Roth goes and gets through six innings," Scioscia said. "It doesn't have to be one, but I think we can back him up with some guys if we have to. I think he's a good candidate, and it gives us more options where we can use Jerome if we have to."
Williams threw 36 pitches in three innings on Sunday, while Roth's last appearance was just four pitches on Monday night.
The Angels selected Roth in the ninth round of the 2012 Draft. Roth spent 2012 in rookie ball and began the this season with Double-A Arkansas.
"My arm feels good," Roth said. "I haven't thrown out of the 'pen on back-to-back days yet. I think I'll be all right. My last start in Double-A was five innings. I'm just going to go out there inning by inning, as cliché as that sounds. Go out there and have some fun."
Since making his Major League debut on April 13, Roth has appeared in four games, thrown five innings and posted a 3.60 ERA.
Alden Gonzalez is a reporter for MLB.com. Read his blog, Gonzo and "The Show", and follow him on Twitter @Alden_Gonzalez. William Boor is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.