The Boston Celtics finally found their legs last night, running past the Houston Rockets 109-80 to move within a game of clinching their 14th National Basketball Association championship.

Boston put the game out of reach early, snapping off a 19-1 run midway through the first quarter. The streak, keyed by Robert Paris and Cedric Maxwell, put the Celtics ahead by 15 after one, and the rest was a cakewalk.

The Celtics meet the Rockets again tomorrow night, this time in Houston; and unless Houston finds some way to rein the Boston fast break, the series--which currently stands at 3-2--will end there.

Maxwell had 28 points, his career playoff high, and a double-digit rebound total. Parish ended the game with 18 points, while the Rockets primary engine, Moses Malone, scored 20.

Larry Bird began the first-quarter streak that put the Celts in control with a 12-ft. jumper, followed by a spinning Maxwell layup. Malone hit a freethrow, and Chris Ford fastbreaked a layup. And after that--Parish.

The 7-ft. center scored eight consecutive points, and then blocked a Houston shot to set up a Maxwell 3-point play.

Big Help

The Celtics widened their advantage to 59-37 at halftime, holding Houston to a single field goal in the last 7:40 of the second quarter, and keeping the Rockets away from the basket entirely in the first 4:26 of the third.

Houston came no closer than 22 points in the fourth quarter.

The Celtic runaway ended Houston's nine-consecutive-game record for holding opponents below 100 points.

If Houston somehow wins tomorrow night, the series will move back to the Hub for a Saturday finale; if the Celtics wrap it up, they'll come home to an airport reception with one more flag to hang in the rafters.