Delgado hurt his right hip when he slid on a triple Sunday, and did not play in Monday night's 7-1 win over the Marlins. The slugger had an MRI exam Tuesday, and manager Jerry Manuel said he planned to rest Delgado in the series finale Wednesday.
"He should be ready to go Friday," Manuel said.
The Mets are off Thursday and play at Philadelphia this weekend.
Delgado said there was inflammation in his hip joint and hoped the rest would prevent the problem from becoming a nagging injury. Fernando Tatis took Delgado's spot at first base.
Castillo left in the fifth inning Monday night with a muscle spasm in his back. Asked whether he thought he could play Wednesday, he winced.
"We'll see what happens," he said.
Alex Cora started at second base against the Marlins.