The first rule in making friends with a bear is to act casually. V-e-r-r-r-ry casually. If you're afraid, the bear will know it and you will have a short and unpleasant relationship. Be confident. Say something nice. Toss a sugar cube.

This approach really works, according to no less an authority than Rustam Kaseyev, bear trainer at the Moscow Circus, which opens tonight at Capital Centre. "It was in the sweetest way" that he made friends with Masha, said Kaseyev, who speaks some English but was helped by interpreter Igor Gueja.

Masha was a "quite ferocious" bear when Kaseyev received a call several years ago from a summer camp for children in Moscow. It was September, the children had gone back to school, and nobody was around to feed sweets to Masha, who was living in the camp's zoo. She grew very ill-tempered. The man on the phone told Kaseyev: "We have a bear and nobody can approach it. If you want it, you can come and take it."

Kaseyev, intrigued, accepted the offer, even though he already was occupied with bears: He had six of them living with him, his wife and two children in their three-room apartment on the 12th floor of a 14-story Moscow highrise. ("The rooms are fairly large," he said.)

This arrangement was sometimes disconcerting to the other tenants, and Kaseyev's wife, Nellie, who also trains, said, "Once we overheard the neighbors say, 'See, they allow dogs in here, and now we have bears.'"

But Kaseyev said he believed the way to make the bears feel at home was to share his own place with them. And because an old German bear philosopher once said, "It's through the animal's stomach that you make him friendly to you," Kaseyev gave his bears the run of his kitchen. They grew very big, very quickly.

Admittedly, Kaseyev said, there were some rough moments. The bears were not always friendly to each other; they "alternated love and hatred." And, eventually, he said, "the apartment needed general repair." But he considered that a small price in preparing Kesha, Katya, Gerei, Yula, Dyoma and Ponchik for the circus.

Because it was so crowded at the apartment, and the wild Masha presumably was in no mood to share honey with six other bears, Kaseyev took her to his dacha, outside Moscow. There, he climbed into a cage and sized her up, saw in her what she is today: the 9 1/2-year-old, 280-pound star bear of the Moscow Circus, the big mamma of all 18 bears.

It took a man of Kaseyev's vision to see this because when he got in the cage, Masha was crouched in a corner ready to charge him.

Kaseyev did not take this situation lightly. He said it was "hell" having his apartment full up with bears while having to deal at the same time with Masha. But he said, "I could see potentially all the efforts would pay off, Masha was special. She would be the leader of the bears." Little bears, he explained, learn from big bears, as well as bear trainers. So Masha would help him. He sweet-talked her.

Masha was not immediately persuaded. She stayed crouched, listened to Kaseyev's sweet nothings, and accepted the sugar cubes he slid across the floor to her. For his part, Kaseyev did not linger. "I did not want to make a temptation of my future and her future," is the way he put it. He visited the cage briefly six or seven times a day, "speaking mildly to her, consoling her."

As he describes the experience, Kaseyev, a lean man of about 5 feet 10, crouches and looks up at an imaginary Masha hovering over him. The whites of his eyes grow larger, his arms reach out.

"In 10 or 12 days," he said, "I noticed a change of mood. Her eyes were no longer frightened. Her ears were not as close to her scalp. By 20 days, she was waiting for my footsteps, peering out. She stood close to me, and took sugar from my hand. I combed her hair.

"After 24 days, she came out of the cage with me for a walk. From time to time she stood on her hind legs. (Such a trick rates a sweet every time.) She tried to claw me, and bit my leg" - but not the hand that fed her honey, sugar, cookies, cheese, cranberries, cabbage and oranges, her favorite foods. (Never meat, Kaseyev said, because it "awakens wild instincts" in a bear.)

After eight months, Masha - happy in her muzzle and dancing to Russian folk songs - was ready for the single ring of the Moscow Circus. Her arrival solidified Kaseyev's reputation as a bear trainer; he had formerly been an acrobat, joining the circus after studying physical education and acting. He said his father, who came from a village in the Republic of Bashkir near the Urals and cut furs for clothing, did not approve of circus life, nor the esoteric pursuit of bear training.

But Kaseyev enjoyed good fortune, learning bear training from the master, Filatov, and meeting his wife, Nellie, a construction engineer who took to bear training so naturally that she amazed Kaseyev, who had put so much time in on it. In addition, she had invaluable bear connections, friends in Siberia who would give them the best little bears a trainer could ask for.

Lately, the pair even had managed to get the bears "to violate the laws of nature" - they have not knocked off to sleep for several weeks while other bears have. By keeping them awake and busy, the Kaseyevs have made them forget they are bears. "If they had hibernated," said Kaseyev, "this American tour would have had to be canceled."