Bath fly-half Davis was out of action for 17 months with a knee injury
Bath and Leicester have added to their Heineken Cup squads ahead of their last-eight match on Saturday, 11 April.
Clubs are allowed to add a maximum of three new players to their registered squad for the knock-out stages.
Fly-half Ryan Davis, who made his comeback from long-term injury against Sale, prop Laurence Ovens and lock Scott Hobson boost the Bath ranks.
The Tigers have opted to bolster their back-row options with the addition of Craig Newby and Ben Pienaar.
Bath, who are one of three clubs along with Ospreys and Cardiff Blues to use the full allocation allowed, travel to Leicester for their quarter-final at the Walkers Stadium.
The winners will face the Blues or Toulouse in the semi-finals.