The Wales World Cup forward has been out for more than a month with a groin strain but has been passed fit for the Brewery Field clash on Friday.
As has former England Under-21 prop Chris Horsman whose return to the front-row allows Gethin Jenkins to return to his favoured loosehead position in the scrum.
That comes as a huge boost for the Warriors who know they must beat last year's Heineken Cup finalists if they are to have any realistic chance of qualifying for the quarter-finals at the first time of asking.
Their hopes took a dent last weekend following their hard-fought 17-11 defeat to London Wasps at Bridgend.
'The boys who played against Wasps gave more than 100 per cent and that's all I can ask for as a coach but I thought we lacked a bit of bulk and lineout presence and we have now got that back,' said Warriors coach Lynn Howells.
'We have also now got a bench that can make a difference to a game, which is important as we saw against Wasps.'
Wales scrum-half Gareth Cooper is selected ahead of Sililo Martens in the other change to the Warriors team.
Celtic Warriors: G Wyatt; D James, S Parker, G Thomas, A Havili; C Sweeney, G Cooper; G Jenkins, M Davies, C Horsman, D Jones, R Sidoli, M Molitika, R Parks, C Harris. Replacements: M Rees, C Loader, B Cockbain, N Kelly, S Martens, N Jenkins, J Bryant.