"Feeling stronger and stronger every day," he said. "Feeling better each day, so the progression is going well. So we're on target for where we ought to be right now."
Boxberger answered "probably" when asked if he'll need a rehab assignment before returning, but he isn't sure.
"We haven't gotten that far up the road yet," he said. "We still need to get through the next couple of weeks and kind of map out how things are going to go later on."
Boxberger said he will "hopefully" get off a mound "pretty quickly."
"[I don't want to] rush anything, because I don't want to [have any setbacks]," he added. "As long as I'm feeling good, though, I'll keep going at the pace that we are."
Boxberger didn't like watching Sunday's season opener from the disabled list.
"It's my first day watching on the DL and not being able to play in the game," he said. "It's a little bit of a different outlook. Hopefully, it will be short-lived."
• Utility player Taylor Motter, 26, was selected as the winner of the 2016 Al Lopez Award, given to the most outstanding Rays rookie in Spring Training. In his first Major League camp, he batted .250 with a home run and four RBIs while playing six positions in the field.
• According to the Elias Sports Bureau, Rays pitchers tied the modern Major League record for a nine-inning Opening Day game with 16 strikeouts, equaling the mark of the 2005 Mets staff (April 4 at Cincinnati).
• Evan Longoria's two hits on Sunday moved him past Fred McGriff to establish a new club record for the most hits collected in Opening Day games, with 11.
Bill Chastain is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.