Last night at the Kennedy Center Concert Hall Mstislav Rostropovich conducted a reduced National Symphony in his first chamber orchestra program since he became music director.And it was on of the most utterly enjoyable performances he has ever brought us.

Small wonder that Rostropovich has a real flair for this field -- on the cello he is, after all, one of the world's leading chamber music players.

But the mastery of Mozart style he brought to the first half of the program was more of a surprise. Neither he nor the NSO has all that good a track record with Mozart the brooder or Mozart the urbane (too much over-exertion and too many rough edges). But last might it was mostly Mozart the extrovert, in the 29th symphony and the bassoon concerto.

Rostropovich was much in his element. The balances and dynamics were beautifully calculated. It was not definitive -- the symphony can take a crisper opening, and the orchestra's principal bassoon player, Kenneth Pasmonick, had to be a little too cautious in the concerto.

After intermission there was Dvorak's early string serenade. Few works can match it for the delectable balancing of the serene with the spirited. And, of course, it is exactly Rostropovich's Slavic musical meat.

Unfortunately the program will not be repeated.