Late last night, National Symphony Orchestra Musical Director Mstislav Rostropovich told friends in the NSO, "You watch. Paris is my city. You will see."

Indeed, he seemed to have Paris in his pocket. Tonight's 8:30 concert in the Salle Pleyel did not end until 11:10, and even at that hour nearly the entire audience was still shouting "Slava! Slava!" and cheering the National Symphony Orchestra.

The Pleyel is where Chopin and Liszt played, as have hundreds of other greats, though the large concert hall has been recently renovated. The stage is completely surrounded by wood, and the sound is powerfully projected into the 3,000-seat house.

The audience's reaction was as Rostropovich predicted. At the end of the Second Symphony of Schumann, which ended the first half of the program, the cheers began and went on for a long time.

When Rostropovich, finished the Shostakovich Fifth in the second half, the sound from the audience was like rolling thunder that went on for 20 minutes, lasting through three encores. When Rostropovich announced the first of these, the overture "Gaite' Parisienne" by Offenbach, there were exclamations of delight at the witty choice. Enthusiasm mounted through the Paganini Perpetual Motion and stormed through the house again after the "Death of Tybalt" from "Romeo and Juliet" by Prokofiev.

The members of the National Symphony played extremely well, much of the time brilliantly. Their achievment is the more remarkable in light of the fact that this is their fourth city this week, and London faces them tomorrow.

Such a schedule inevitably takes its toll in mounting fatigue and illnesses. Tonight, just as Rostropovich was ready to enter the stage to begin the concert, Concertmaster Miran Kojian proved too ill to go on. Tour doctor Jerry Martin sent him back to the hotel with the kinds of medicine that can help someone afflicted with intestinal flu. Assistant Concertmaster Andres Archila took his place.

Rostropovich's open affection for this, his adopted city, where he and his wife soprano Galina Vishnevskaya have a magnificent apartment , was apparent throughout tonight's concert. The conductor demanded of his musicians every possible ounce of energy and beauty. There were times when things went into a kind of overdrive, coming out louder and more intense than they needed to be. But it was easy to see why it happened.

On Wednesday, in Amsterdam's glorious Concert-gebouw, before an audience headed by Queen Beatrix, the orchestra played superbly, winning another prolonged demonstration. On Thursday in Du sseldorf's rebuilt Tonhalle, a round auditorium lined completely in wood, the sound was somewhat dry, but the playing again was top drawer. Tomorrow night the orchestra performs in London's Royal Festival Hall.