"I always carry my first baseman's glove, my third baseman's glove and my catching glove," Pena said. "I always go and help the guys during BP, but now it's not help. It's the real thing. I'm very happy the skipper gave me the opportunity to be in the lineup and continue to be playing."
The Reds don't know how long they will be without Votto, who was diagnosed after the MRI with a left distal quadriceps strain. The disabled list remained a possibility.
If there is a silver lining, Cincinnati can keep Pena's bat in the lineup even after getting Devin Mesoraco back. Mesoraco was activated on Friday from the DL after he suffered a strained left hamstring on April 25.
The switch-hitting Pena, 32, entered Friday batting .282 with three home runs and nine RBIs.
Manager Bryan Price noted that besides Pena, third baseman Todd Frazier or prospect Neftali Soto could get some time at first base too. As for playing an unfamiliar position, Pena wasn't concerned.
"It's not like I'm playing shortstop or second base," Pena said. "It's one of the things I just have to go and sit down with [coach Freddie] Benavides and see where he wants me to play the lefties and different positioning like that. I know I'm not a Joey Votto. I'm never going to be a Joey Votto, but I'm going to go out there and give my team my best."
Mark Sheldon is a reporter for MLB.com. Read his blog, Mark My Word, and follow him on Twitter @m_sheldon. This story was not subject to the approval of Major League Baseball or its clubs.