Reeling Portland Timbers faced with new challenges with injuries to Michael Harrington, Diego Chara

BEAVERTON, Ore. – Not that the Portland Timbers needed anymore challenges to overcome, but they’ll be without two of their top defensive players in Saturday’s home matchup with the Columbus Crew (10:30 pm ET; MLS Live).

Defensive midfielder Diego Chara will miss up to two weeks, the team said, after breaking his hand in Sunday’s match against the LA Galaxy. He underwent successful surgery to stabilize a fractured third metacarpal bone in his left hand, the team announced Tuesday.

In addition, head coach Caleb Porter said left back Michael Harrington will likely not be available after spraining his ankle against the Galaxy.

The ominous injury news comes just as the Timbers are working to address a series of defensive lapses over the last month – highlighted when the backline allowed an easy Robbie Keane header for a goal in stoppage time of their 1-1 draw with the Galaxy.

Porter said that nine of their 16 goals allowed in 10 games have come from either crosses in the run of play or set pieces.

“So we’re going to work on that, we’re going to train it and we’re going to correct it,” Porter told the media following a recent training session at the team facility.

Porter said the mostly likely course of action when it comes to address the starting lineup against the Crew will be the same substitutions made when Chara and Harrington came off against the Galaxy. Ben Zemanski replaced Chara, and Alvas Powell came on for Harrington and swapped places with right back Jack Jewsbury.

“I thought they did pretty well,” Porter said of Zemanski, Powell and Jewsbury at left back.

The Timbers also brought in former Columbus Crew defender Danny O’Rourke on trial. Porter – who coached O'Rourke as an assistant at the University of Indiana – said, depending on his performance, he could factor into the lineup in future games.

“He’s a guy that brings a lot of experience,” Porter said of O’Rourke. “He won an MLS Cup with the Crew; he was a leader on that team. He’s another guy that brings I think a winning mentality. He’s versatile and can play anywhere along the back four and at holding mid. With Mikey out, he could be another option in any of those four spots across the backline.”

The Timbers’ defensive issues have been just one problem in a sluggish start to the season that currently sees them in last place in the Western Conference with just one victory. And despite the key absences, Porter said things need to turn around quickly if they stand a chance to advance to the MLS Cup Playoffs.

“The urgency has been there,” Porter said. “… The media especially and I think to some extent the players, they don’t always know how urgent it is – certainly the media doesn’t, whatsoever – so I laid out how urgent it is. And it’s pretty simple when you look at historical factors, usually 1.5 points per game gets you in the playoffs.”

And with nine points so far, Porter said Portland need 42 points out of their next 24 games.

“If we get that, we’ll be in the playoffs,” Porter said. “I’m confident of that.”

Dan Itel covers the Timbers for MLSsoccer.com.