USMNT's Walker Zimmerman Out for Gold Cup as Berhalter Mulls Changes

Zimmerman suffered a hamstring injury vs. Canada, leaving the U.S. thin at center back for the knockout stage.

The U.S. men's national team won its three group matches at the Concacaf Gold Cup, but it didn't emerge from the opening phase unscathed.

Center back Walker Zimmerman has been ruled out with a hamstring injury, which he suffered in the first half of Sunday's win over Canada. He was replaced 15 minutes into the match by Donovan Pines.

Zimmerman captained the U.S. in the last two group games and was the most experienced center back on what's generally a young and inexperienced team. Miles Robinson, James Sands and Pines are the remaining central defenders on the squad. The trio entered the Gold Cup with a combined three caps, all of which belonged to Robinson.

The U.S. has up to 24 hours before its quarterfinal match to make any injury replacements (players must come from the U.S.'s preliminary roster), and prior to making anything official, manager Gregg Berhalter has called on New England Revolution center back Henry Kessler and San Jose Earthquakes forward Cade Cowell into camp to join training (winger Paul Arriola has also been dealing with an injury and is a candidate to be replaced). Neither player has a senior U.S. cap, though both took part in a combined U-23, senior team training camp in January.

The U.S. will play Jamaica in the quarterfinals after the Reggae Boyz fell to Costa Rica Tuesday night in their group finale to settle for a second-place finish. The winner of U.S.-Jamaica will face off against either El Salvador or guest nation Qatar in the semifinals. Those quarterfinal matches take place in a doubleheader on Sunday night at AT&T Stadium in Arlington, Texas.

Canada-Costa Rica and Mexico-Honduras are the matchups on the other side of the bracket, with those quarterfinals happening a day earlier at State Farm Stadium in Glendale, Ariz. The final is slated for Aug. 1 at Allegiant Stadium in Las Vegas.