The Wales international, who had recently returned to action after dislocating his shoulder, sustained a thigh injury in Saturday’s defeat at QPR.
‘Jonny will be out for a month,’ Coleman told Sunderland’s official website. ‘It’s a grade two tear in his quad. That’s disappointing because it has been a tough season for Jonny, very stop-start.
‘I can’t get him fit and keep him fit and that’s a shame because he is such a good player and in full flow as a Sunderland player the supporters would love him.
‘We haven’t managed to see that because unfortunately he has had bad luck.’
Coleman confirmed fellow midfielder Darron Gibson is edging closer to full fitness, but remains ‘a few weeks away’ as he recovers from a groin injury sustained in early January.
Cardiff remain unhappy with Derby's decision to postpone Sunday's Sky Bet Championship game at Pride Park.
Dundee United boss Csaba Laszlo has been left hoping for St Mirren to slip up in the race to seal promotion to the Ladbrokes Premiership.
Crewe will consider starting Chris Dagnall when they host Forest Green on Tuesday.