Morneau went 0 for 3 with a strikeout in his return, an 8-1 loss to the Orioles.
Morneau is dealing with a bone bruise on the top of his right foot after a foul ball. He was the designated hitter against the Orioles, batting in his customary cleanup spot.
"He's moving around," Minnesota manager Ron Gardenhire said. "He's doing OK. His foot's better. He's still a little sore, but he's ready to get back out there, start doing a little swinging."
Morneau was hitting .161 in eight games since being activated from the disabled list Aug. 12. He's been limited to 63 games this season after being put on the DL with a wrist strain and then having surgery to remove a herniated disk fragment in his neck.
In other injury news, Minnesota pitcher Nick Blackburn was diagnosed with an entrapped nerve in his forearm following an MRI exam Monday. He will be shut down for two weeks before being re-evaluated.
"He doesn't have a muscle strain," Twins trainer Rick McWane said. "He has no ligament damage, no tendon damage, so that's all good."
Blackburn is 7-10 with a 4.49 ERA in 26 starts. McWane said he expects the right-hander to resume pitching by the end of the season.
Twins shortstop Tsuyoshi Nishioka was available off the bench after missing three games with pain in his lower back and oblique area. Nishioka hit in the cage and took grounders before the game without any issues.
McWane said right-hander Scott Baker, on the disabled list with a flexor strain in his pitching elbow, started his throwing program.
Minnesota has used the disabled list 23 times this season and has fallen to fourth in the AL Central after briefly getting back into contention at the All-Star break.
Denard Span is spending a week away from the team to rest and recover from migraine symptoms. Span missed 56 games with a concussion, then briefly returned before having to go back on the disabled list Aug. 18.
Second baseman Alexi Casilla (hamstring) ran on the field before Tuesday's game and didn't report any problems.
Information from The Associated Press was used in this report.