Ireland fly-half Jonathan Sexton is a fitness concern for Saturday's Six Nations clash against France.
Sexton was reported to have suffered a "tight thigh muscle" during kicking practice in Paris on Friday so Ronan O'Gara is now on stand-by to start.
Paddy Wallace, who had been scheduled to play for Ulster against the Dragons on Friday, has been called into the Ireland squad as cover.
An Ireland team spokesman told BBC Sport that Wallace had been brought into the squad as a "precaution" and that Sexton's fitness would be further assessed on Saturday morning.
Munster's Earls, who pulled out of last weekend's match because his recently-born daughter was unwell, replaces Fergus McFadden.
Ulster flanker Stephen Ferris retains his place after being cleared by a citing commission on Wednesday.
Coach Declan Kidney welcomed the return of Earls.
"Keith has been bubbling away since he has been back with us and has trained well. It was tough on Fergus to lose out," Kidney said.
Ireland have triumphed in Paris just once since 1972 and have beaten France only once in 12 meetings at all venues dating back to 2003.
"There's a lot we have to improve on. Some of the silly errors we made against Wales we must cut out," said captain Paul O'Connell.
"Against France away from home you need to start well. It is frustrating that I haven't beaten France in Paris, but we have a team that can do it."
The weather is also forecast to remain very cold which will not help matters as it is an evening kick off in Paris. Alternate dates have been proposed should the game be unplayable.
