"I made sure he had his outfield glove on the bench so he was ready to go."
After reliever Jerome Williams walked first baseman Paul Goldschmidt, Porter brought Sipp back in from the outfield and put him back on the mound to face D-backs catcher Miguel Montero.
He then struck out Montero before Porter relieved him for good, bringing in Kyle Farnsworth.
Porter said part of the reason he moved Sipp back and forth from the outfield to the mound was so he could stay away from long reliever Rudy Owens.
"The last thing you want to do is bring your long guy into the game in the eighth inning," Porter said. "Let's just say we keep the lead and then they end up tying it in the ninth. Now you don't have a long guy. At that point, you go with the short guys that you have."
Sipp had never played a Major League inning at any position other than pitcher, but he did play outfield while he attended Clemson University and played in left field for part of one game for Triple-A El Paso this season.
"I played that in college, Clemson. But I thought those days were behind me," Sipp said. "Anything can happen coming over, playing in the National League."
Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. Adam Lichtenstein is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.