The Rapids will be without the two center backs that started the first four matches on Saturday when they face the Portland Timbers at Dick's Sporting Goods Park (4 p.m. MT).
An MRI on Diego Calderón's right knee on Tuesday determined that the Ecuadorian requires an exploratory procedure to learn the extent of the injury suffered against the LA Galaxy last weekend. The team is awaiting the surgery on Thursday in order to determine the length of time he will miss.
Calderon was injured in the first half of the Rapids’ match at the LA Galaxy on March 23 when he collided with the goalpost after clearing a scoring attempt off the goal line.
Colorado will also be without center back Drew Moor who is suspended after receiving a red card against LA.
In addition, the team also lost midfielder Pablo Mastroeni to injury in the first half of the same match, and the captain will be out about two weeks rehabilitating a strained left quadriceps.