Wigginton, who said his strained oblique felt good during a rehab start in Colorado Springs on Thursday, was in the lineup at third base on Friday as the Rockies opened a three-game series with the Padres.
The Rockies are in dire need of production at third base, where Stewart was hitting just .064 with no home runs and one RBI. Jose Lopez is hitting .155 and Wigginton, who injured the oblique while sliding into second base at Wrigley Field on April 17, is batting .233.
Injuries cost Stewart the majority of Spring Training. He was optioned to Triple-A on April 19 after starting the season 2-for-26 with 11 strikeouts. Stewart returned to the Rockies on May 3 after a successful stint with the Sky Sox, but was just 1-for-21 in his return.
"I'm just going to try to go down there and have fun," Stewart said on Friday, shortly after learning of his demotion. "I felt pretty good. Obviously the hits weren't there, but I felt pretty good in the box since I got back. I'm just going to go down there and try to do well like I did before and get back."
Rockies manager Jim Tracy said the decision to option Stewart was a difficult one, but he is desperately looking for a spark in a lineup that entered Friday hitting .232, third-worst in the National League.
"We are searching for offense, and he is struggling mightily offensively," Tracy said. "For Ian Stewart to be a part-time player, that isn't going to work. ... It's going to be a period of time until he convinces himself and we are convinced of the fact that it's something that he has a complete handle on."
Wigginton showed signs of life in his last game before heading to the disabled list, when he went 3-for-4 against the Cubs.
"I felt pretty good last night [in Colorado Springs] considering I hadn't been in there in 15 days," Wigginton said. "I was pleased with that, so we'll just have to see how it shakes out here."
Nick Kosmider is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.