The Reds activated Hayes (back) from the 10-day injured list Friday, Charlie Goldsmith of Fox 19 Now Cincinnati reports.
Hayes looked sharp at the plate on his rehab assignment, going 7-for-12 with one home run in three games with Triple-A Louisville. He slashed an ugly .142/.195/.225 in 44 contests with the Reds before going down in late May with a bulging disc in his back. Hayes will get some starts at third base on days Sal Stewart plays another position, but it's uncertain how often the veteran infielder will ultimately get into the lineup.