Midfielder Diego Chara and defender Amobi Okugo have joined the Portland Timbers' growing injury list.

According to Timbers coach Caleb Porter, Chara suffered a hamstring strain during Sunday's game against the Seattle Sounders and will miss the next four weeks, while Okugo suffered an MCL sprain on Clint Dempsey's stoppage time equalizer in Sunday's match and will miss the next 4-6 weeks.

Liam Ridgewell, who has been dealing with a quad strain, has not yet trained this week and will not be available for Saturday's game against Sporting Kansas City. Porter said that he did not yet know if Ridgewell would be healthy enough to play when the Timbers host the Chicago Fire on July 5.

"It's not progressing as quickly as we thought," Porter said. "He's still having some discomfort in that quad."

Darlington Nagbe, who left Sunday's game against the Seattle Sounders with a hamstring injury, remains questionable for Saturday's match against Sporting Kansas City.

"We won't rule him out yet, but he hasn't trained this week," Porter said. "So, he's definitely questionable for the match. We'll know in the next several days."

Timbers winger Jack Barmby reinjured his calf in training Tuesday as well. Porter said Barmby will now be out for "another couple of weeks."

Timbers midfielder David Guzman has also joined the Costa Rica National Team for the 2017 Gold Cup and will not be available Saturday when the Timbers take on Kansas City.

With all the injuries and absences, the Timbers will be heading to Kansas City Saturday with limited options at center back and defensive midfield.

Porter even had defender Zarek Valentin, who has never played holding midfield, train at defensive midfield Wednesday. If Nagbe can't play against Kansas City, Valentin could be a real option at the position Saturday.

"At holding mid and center back, we're as thin as we've ever been," Porter said. "We're going to go into the game and have a group of guys that I know will put their best foot forward and I believe we will have a chance to win the game and get three points."

-- Jamie Goldberg | jgoldberg@oregonian.com

503-853-3761 | @jamiebgoldberg