Francis incurred the injury early in the game, but after the length of the outing, he and the club were optimistic that he might be able to stay on track for his next start Sunday.
"I felt it in the second inning on a pitch," Francis said. "I didn't slip or anything. It was just a regular pitch. I came in after the inning and told [assistant athletic trainer Scott Gehret], and they wrapped it up. I was able to keep pitching, so I felt like hopefully it would get better quick. It was sore yesterday, and it's just as sore today. I didn't see any way I could throw a bullpen. [Head athletic trainer Keith Dugger] said about seven to 10 days. You never know with these kinds of things."
Francis, 32, is 2-3 with a 6.00 ERA in eight starts this season, and ranks second all-time among Rockies pitchers in wins (63) and innings pitched (1,031 2/3), trailing Aaron Cook in both categories. In addition to the groin injury, he also banged his knee sliding into second during Tuesday's game, but the knee is not an issue.
"The way he pitched, we didn't think it would be a long-term issue," said manager Walt Weiss. "But he's been really sore ever since, and particularly today. The fact that he threw a gem the other night and got through six innings banged up says a lot."
The Rockies called up reliever Rob Scahill for his second stint with the club this season. Scahill pitched three scoreless innings in the first game of an April 23 doubleheader with the Braves and is 2-0 with a 5.40 ERA in 11 appearances across 26 2/3 innings in Triple-A Colorado Springs.
The Rockies will need to make another move before Sunday's series finale with the Giants, when Francis was scheduled to pitch against Barry Zito. The likely candidate is Tyler Chatwood, who is scheduled to pitch Saturday for Colorado Springs. Chatwood is 1-0 with a 3.00 ERA in two starts for the Rockies this season, and is 2-1 with a 3.14 ERA in five starts at Triple-A, including a shutout May 7 against Iowa.
Francis hopes to be back in the Rockies rotation when he's eligible in 15 days.
"That's what I'll work for," Francis said. "We all want to be out there on the field."
Owen Perkins is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.