Zack Steffen injured a knee and became the second goalkeeper dropped from the United States' training camp ahead of the Concacaf Gold Cup. Steffen was hurt during training Tuesday and returned to the Colorado Rapids for more exams, the U.S. Soccer Federation said Wednesday, and he is now set to miss the tournament. A source with knowledge of the knee injury said Steffen is expected to miss anywhere from four to six weeks. A Rapids spokesperson declined to elaborate on the injury and would only confirm that Steffen was en route back to Denver, where he would be evaluated further. The USMNT will play friendlies against Turkey and Switzerland on Saturday and Tuesday, respectively, ahead of beginning its Gold Cup campaign against Trinidad and Tobago on June 15. Mauricio Pochettino's side will face further Gold Cup group matches against Saudi Arabia (June 19) and Haiti (June 22). Steffen had been in excellent form for the Rapids so far this season, and the injury comes at an inopportune time for the former Manchester City goalkeeper. After he was surprisingly left off the U.S. roster for the 2022 FIFA World Cup, Steffen had worked his way back into the USMNT frame and looked sharp in a 2-0 win over Panama in January. He was expected to challenge incumbent starter Matt Turner for playing time following a club season with Crystal Palace in which Turner played in only a handful of cup matches with zero league appearances. Now that task will fall to New York City FC's Matt Freese and the Chicago Fire's Chris Brady after Columbus goalkeeper Patrick Schulte injured an oblique on May 24. Information from The Associated Press was used in this report.