updated 9:28 p.m. ET May 15, 2008

INDEPENDENCE, Ohio - It’s do or summertime for the Cleveland Cavaliers.

One more loss, and a second straight Eastern Conference title is history.

One more win, and it’s back to Chowderland for Game 7.

After squandering a 14-point lead at Boston in a hail of missed free throws and getting entangled by the Celtics’ spiderweb-like defense in Game 5, LeBron James and his teammates are down 3-2 and facing elimination from the NBA playoffs on Friday night at Quicken Loans Arena.

They’ll go into Game 6 short-handed.

Guard Daniel Gibson, one of the club’s best perimeter shooters and a star in last year’s postseason, separated his left shoulder going for a loose ball early in the fourth quarter of Game 5 and will need a minimum of one week to recover.

The Cavaliers may be done before he’s well.

“It’s something we didn’t want to happen,” James said following a light workout Thursday. “It’s kind of the tale of our season — a guy goes down in the heat of a playoff series. He’s very key to our team. It’s not good seeing a guy who is that key to your team in a suit.”

Gibson underwent an MRI on his shoulder after the club returned from Boston. He was not available for comment. As a few of his teammates got in some extra work, the second-year guard struggled to slip a T-shirt over his head before sitting on a courtside bench alongside James.

Gibson made two 3-pointers and scored 14 points in Cleveland’s win in Game 4. In last year’s Eastern Conference finals, he scored 31 points — 25 in the second half — as the Cavs put away the Detroit Pistons in Game 6 to advance to their first NBA Finals.

For them to force a Game 7 in Boston, the Cavaliers may need someone else to come off the bench and come through.

“We’re not looking for a spectacular game from anybody,” said James, who scored 35 points on 12-of-25 shooting in Game 5. “We just want to continue to do what we’ve been doing in the two wins we’ve had at home — guys stepped up. We’re not looking for a guy to go out and score 30 points or anything like that.”

Special feature Smooth moves Check out some of the dancers from the NBA. NBCSports.com

Cleveland coach Mike Brown said he hasn’t decided whether to play reserves Devin Brown or Damon Jones in Gibson’s spot. He may just give extended minutes to swingman Sasha Pavlovic, who played only 10 — his average for the series — in Game 5.

The Cavaliers spent most of Thursday reviewing film before practicing their free throws. They went only 28-of-41 (68 percent) from the line in Boston and missed 10 in the second half, but what bothered them most was a lack of intensity in the third quarter, when the Celtics outscored them 29-17.

Center Zydrunas Ilgauskas, who scored just six points on only five shots in Game 5, couldn’t explain Cleveland’s passivity after leading 43-29 with less than four minutes to go in the first half.

MORE FROM NBA

NBA Section Front

Will LeBron be a Knick, Net or remain a Cav?   Jazz to extend Deron Williams for $70 million Clippers sign swingman Azubuike to offer sheet O'Bryant works out for first time as a Celtic NBCOlympics.com: Durant, Rose on select team Ventre: Clippers' chaos kicks off NBA's reality show Rumors: Kings want Mavs' Howard for Artest Special feature: NBA top free agents Latest NBA videos Rotoworld: Latest player news, rumors and more NBA Section Front   Add NBA headlines to your news reader: