Boston Celtics forward Kevin Garnett reacts after scoring and being fouled in the third quarter of Game 5 of the 2010 NBA Finals basketball series in Boston, Massachusetts, June 13, 2010. [Agencies]

BOSTON - The Boston Celtics used the outside shooting of Paul Pierce and a superior inside game to defeat the Los Angeles Lakers 92-86 in the NBA Finals on Sunday and move within one victory of a record 18th championship.

Pierce had his best game of the series, scoring 27 points on 12 of 21 shooting from the floor. But the Celtics won the battle inside where they outscored the Lakers 46-32.

Boston holds a 3-2 lead but the best-of-seven series now shifts to the Staples Center in Los Angeles where the Celtics must either win Game Six on Tuesday, or, if necessary, Game Seven on Thursday.

Los Angeles guard Kobe Bryant had 38 points, including 19 in the third quarter, but the Lakers suffered from a lack of balanced scoring.

Boston led by six points at intermission and although Bryant connected on seven of nine shots in the third period -- including three from long range -- the Lakers' deficit increased to 73-65 during the span.

The Lakers, who are trailing a series for the first time this post-season, trimmed the Celtics' lead to 87-82 on two foul shots by Bryant with 1:30 remaining.

Los Angeles forward Ron Artest missed a pair of free throws with 43 seconds to go and Boston countered with a lay-up by Rajon Rondo eight seconds later to push the lead to 89-82 and ignite the crowd of nearly 19,000 at the Boston Garden.

Bryant had only 10 points at intermission before coming alive in the third period. He hit 13 of 27 shots for the game, including four of 10 from beyond the arc.

"Kobe struggled the first half," said Lakers coach Phil Jackson. "The second half I thought he was his dynamic self again and got us back and going."

Pau Gasol added 12 points but he was the only Laker other than Bryant to reach double figures.

Boston's inside play helped them shoot 56 percent from the floor while the Lakers managed only 39.7 percent. Los Angeles stayed in the game by hitting seven of 19 from long-range.

 Los Angeles, whose biggest lead was just two points in the opening period, connected on 17 of 26 free throws while his Celtics hit nine of 13.