Tchaikovsky's majestic musical epic "Manfred" dominates any program on which it is placed almost as inevitably as does a Mahler symphony. In length, in scale, in complexity and in intensity, "Manfred" leaves all else in the shade.

And that is especially the case when played with the commitment and conviction that Mstislav Rostropovich and the National Symphony showed last night, in the first of this week's four separate programs previewing the orchestra's April tour of the Far East.

Any feelings this listener may have had in previous seasons that Rostropovich's way with this magnificent work, based on Byron's poem, is a little too prolix and episodic were rendered inoperative by last night's grand performance. Once, the conductor's manner with the heroic introduction seemed to take Tchaikovsky's marking "lento lugubre" a little too "lugubre." But last night the rests that repeatedly stop the movement did not, as a result, mean the loss of the music's pulse and the dissipation of the brooding mood.

The second movement was wonderfully light and fleet.

And just as in last year's interpretation, the flowing balletlike theme in threes that comes near the end of the third movement, first in the cellos and then in the violins, glowed with grace, even though Rostropovich chose to accelerate the pace at that point.

Grandest of all was the lengthy last movement, with its early-on bacchanalian orgies balanced later with the stately apotheosis with organ support that follows the hero's death.

When Rostropovich was planning last year's European tour, he declined to include "Manfred" because it is one of Tchaikovsky's less performed works, and he feared that any critical doubts about its quality might deflect attention from the orchestra itself.

But Rostropovich strongly believes in "Manfred"--it is, quite simply, a masterpiece--and the Europeans' loss is going to be Japan and Hong Kong's gain this year.

Last night's performance was not literally impeccable; how can you expect that when four separate programs are being rehearsed at the same time? But it was never less than splendid--and in the case of the harps and the violas, it was sometimes brilliant.

The first part of the evening was a foil to the Tchaikovsky, in spirit as well as scale.

There was a delectable reading of Prokofiev's brisk, mordant "Classical Symphony." The NSO's greatly improved violins stood out especially well. Their fullness of tone as they launched into the wry gavotte would have been unheard of, and unheard, several years ago. And Rostropovich's funny slowdown of the gavotte's last measures is delightfully deft.

The orchestra's strings sounded fine in Barber's ecstatic "Adagio for Strings," which is just about as lovely as way to open a concert as there is.