"He's not going to play today," manager Bo Porter said. "He went in the cage, he did BP and will go throw. "He's going through the whole routine, and then we'll examine what degree of soreness, if any, is there and move forward."
The Dominican Republic native is expected back sometime this weekend, though whether he'll start before the Astros head off for a 10-game road trip remains in doubt.
"He's no disabled-list threat, at least," Porter said.
Villar injured his thumb during the fourth inning of Houston's 15-10 loss to Boston when he jammed it in the third-base bag as he was caught stealing. He exited the game after making an error in the sixth inning.
The caught stealing was a rare sight, as the speedy shortstop has already swiped 10 bases in 15 games since being called up from Triple-A Oklahoma City on July 21.
Villar had a new splint on the thumb Friday and said it was more comfortable, with the swelling basically gone and pain barely noticeable.
However, there's enough there that swinging right-handed is uncomfortable, temporarily eliminating half of the switch-hitter's repertoire at the plate.
"I can hit with the left hand because it's on top, so no pressure," Villar explained. "The right is tough with the upper hand pushing against [the left] lower hand with the thumb. I'm testing it out. Ready to play today if I can, probably back tomorrow."
Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. Chris Abshire is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.