Mark J. Terrill, Associated Press
Boston Celtics guard Ray Allen, with ball, left right after Game 5 because one of his three children was having "health issues."

BOSTON — The Celtics expect Ray Allen to play when they try for a second time to win the NBA championship.

Kendrick Perkins? Now that's a different story.

Allen rushed from Staples Center after the Los Angeles Lakers' 103-98 win Sunday night that forced a sixth game for tonight in Boston. The reason: "health issues" involving one of his three children.

Perkins watched Game 5 from the bench with a shoulder injury. His availability for Game 6 will be a game-time decision.

As the Celtics waited at LA International Airport on Monday afternoon for their delayed flight to leave, team spokesman Jeff Twiss said he expected Allen to take a later airplane to Boston. And, Twiss said, "I don't believe" Allen will miss the game that could bring him his first NBA title in a 12-year career as a deadeye shooter and give the Celtics their first championship in 22 years.

Allen has two sons and a daughter. Some of the players' family members made the journey to Los Angeles for Games 3, 4 and 5.

The Celtics gave no details, only issuing a statement from coach Doc Rivers that "Ray Allen was forced to leave Staples Center at the conclusion of tonight's game due to a health issue with one of his children."

Allen has been a solid contributor in the NBA Finals — second on the Celtics with 19.2 points and 5.2 rebounds per game — after struggling with his shooting in earlier rounds.

Perkins' presence also has been very important — as shown by his absence in the game that cut Boston's lead in the series to 3-2.

The Celtics' 280-pound center was wearing street clothes when Lakers guard Jordan Farmar ventured into the key and sank two fourth-quarter layups Sunday night. Perkins could only watch from the bench while Pau Gasol yanked down 13 rebounds.

His strained left shoulder kept him from clogging the middle and convincing opponents they might be better off to stay away.

"It probably hurt us, obviously," said Boston coach Doc Rivers. "Whenever you lose, the guy that was hurt or the guy that didn't play becomes very valuable."

Perkins status isn't the only question mark for a team with concerns at other starting spots.

Kevin Garnett said he "played like garbage" in Game 5. Allen's state of mind may be an issue. Rajon Rondo "is just not playing well" even though the ankle he hurt in the series is fine, Rivers said. And Paul Pierce sprained his knee in the series opener.

Still, Pierce has played brilliantly on offense and defense and should continue that when he's back before the ear-splitting cheers of a full house of home fans. Unfortunately for the Celtics, Perkins may be just one of them.

"Perk is a physical guy," Garnett said. "He plays the post better than anybody in this league. That's what he does. When you lose a key guy, you're losing something."

Until this season, his fifth in the NBA, the 23-year-old Perkins was one of several developing youngsters on a struggling team. Then the Celtics traded most of those youngsters before this season for Garnett and Allen. That solidified Perkins' role — the bruiser to go along with All-Stars Garnett, Allen, Pierce and speedy point guard Rondo.

Pierce, Garnett and Allen are The Big Three. Perkins is The Biggest One, at least in terms of space taken up.

"We're used to playing with numerous (different) guys on the court," Pierce said. "We do it all the time in practice with our lineups, so I don't think that's something that's surprising to me. But, at the same time, we have Kendrick Perkins hurt, so that kind of changes things on the rotation side."

Without Perkins, Garnett guarded Gasol and ran into foul trouble. Lamar Odom had an outstanding game — 20 points, 11 rebounds and four blocks — without being hounded by Garnett most of the times he touched the ball.

The Celtics started Leon Powe in place of Perkins, who is 40 pounds heavier and at least two inches taller. Powe played the first 4:59, was replaced by P.J. Brown with Boston trailing 14-5 and never returned.

"We have to start Leon, and P.J. Brown is getting a lot of minutes," Pierce said. "Rajon is suffering from a sprained ankle. So Doc is doing the best he can with the ailments we have on this team."

Rivers could beef up his defense by using 289-pound rookie forward Glen Davis, who hasn't played in the series.

"It hurt not having Perkins out there and with Kevin suffering from foul trouble," Pierce said. "They took advantage of that with Pau and Lamar, so definitely they were aggressive. ... But I know we'll bounce back. Hopefully, we can get Perkins back. If we can keep Kevin out of foul trouble, I think we'll be fine."