Samuel (calf) was spotted on the field in full uniform during the media-access portion of Thursday's practice, Nick Wagoner of ESPN.com reports.
San Francisco will release its second Week 4 injury report later Thursday, when the extent of Samuel's participation will be known. Samuel is back on the field for the first time since suffering a right calf strain in the 49ers' Week 2 loss to the Vikings, and while the expectation remains that he'll miss a second straight contest this Sunday versus the Patriots, his presence at practice suggests he can't be ruled out at this stage.