Updated

By Mark Lamport-Stokes

LOS ANGELES (Reuters) - Stunned, shaken and stirred after being out-played by the Los Angeles Lakers in the opening game of the NBA Finals, the Boston Celtics face an uphill task to claw their way back into the best-of-seven series.

Although Boston are renowned for their gritty and physical approach, they were totally outplayed in that department during a 102-89 loss to the defending champion Los Angeles Lakers on Thursday at a packed Staples Center.

"All night we pretty much let them run what they wanted to run, there was no resistance," Celtics captain and forward Paul Pierce told reporters after his team was out-rebounded 42-31. "I looked up and we gave up 100 points, I haven't seen that in a while. We've got our work cut out for us.

"They (the Lakers) did an excellent job with all the hustle plays. That's a game that we usually thrive in -- the loose balls and 50/50 plays. We've just got to do a better job rebounding the ball and eliminating the opportunities."

Game Two is in Los Angeles on Sunday. Ominously for Boston, Lakers coach Phil Jackson has never lost a playoff series in 47 attempts, with either Los Angeles or the Chicago Bulls, when his team has won the opening game.

"Obviously Game Two is very important," said Celtics guard Rajon Rondo. "We don't want to go back home down 0-2 and giving them the opportunity to try to sneak one of their games in Boston and then come back here with two games to close out."

Boston will host Games Three, Four and, if needed, Five before the series would return to Los Angeles for Games Six and Seven.

Two years ago, the Celtics outplayed and outmuscled the Lakers in the NBA Finals, rubbing salt into their opponents' wounds with a 39-point blowout in the decisive game.

However, two members of Boston's pivotal 'Big Three' in 2008 -- Kevin Garnett and Ray Allen - are now aged 34 and are perhaps not quite the collective force they once were.

Plus, the 2010 Lakers have a starting unit that is taller and younger than the Celtics, an advantage that could be become even more beneficial as this championship series unfolds.

Asked what his team had to do to be more competitive, Pierce replied: "Got to do a better job of stopping their guards from penetrating, a better job rebounding the ball and a better job with Kobe Bryant."

Lakers All-Star guard Bryant weighed in with 30 points, seven rebounds and six assists in Game One.

"I know my team," Pierce said of Boston's bid for their record 18th NBA Championship. "I know we're going to bounce back in Game Two with a lot better effort."

(Editing by Frank Pingue)