Terry Collins tells ESPNNewYork.com the Mets most likely will promote a reliever for Friday's second-half opener in Atlanta.

Collins said a decision will not be made until at least Wednesday. Sandy Alderson previously has indicated the Mets soon are expected to call up lefty reliever Josh Edgin. So that may very well be the choice.

Collins indicated the revised rotation probably now has Jon Niese starting Friday in Atlanta, followed by R.A. Dickey on Saturday and Chris Young on Sunday. There is the potential for Johan Santana to start Sunday instead, but Collins wants to see how Santana responds to Thursday's throwing session during a workout at Turner Field.

Santana originally was scripted for the second-half opener, but a twisted right ankle scrapped those plans.

Miguel Batista will pitch as soon as Wednesday in D.C., according to MLB.com's Anthony DiComo. The Mets can wait until as late as July 21 to use the fifth starter.

Regardless, prospect Matt Harvey is unlikely to step into Dillon Gee's rotation spot right away.

"I don't want to put him in a situation where he can fail," Collins told reporters in K.C.