What a night for Bernie Bickerstaff to make his debut as the acting head coach of the Bullets.

All he has to do is bring Washington into a sold-out Madison Square Garden, match wits with the second-winningest coach in NBA history and try to preserve the Bullets' seven-game winning streak against the league's second-hottest team.

"I never told Bernie it would be easy," said Dick Motta, tongue firmly in cheek. "But there really is never a good time in this league. Every game can have its problems."

Bickerstaff is being thrust into the spotlight because of an operation yesterday to correct cartilage damage to Motta's left knee. The knee surgery was successful, a Bullet spokesman said, and Motta hopes to return to the bench Saturday against Kansas City in Capital Centre.

The operation will deprive Motta of the chance to renew his long-standing rivalry with Red Holzman, who is two places ahead of him on the NBA's all-time coaching victory list.

"I love to coach against Red," said Motta. "He is the NBA. He's been around so long, both as a player and as a coach, and you have to respect him. He's a gentleman and a hell of a coach. You know when you play him, his teams are going to be prepared and he'll be ready for everything you do."

Holzman is regarded as a coaching genius among the NBA old-timers. And what he has done with the Knicks in the two weeks since he took over for the embattled Willis Reed does seem to make him a sports version of Albert Einstein.

New York was a disorganized, ill-prepared, weak defensive club under Reed with a 6-8 record. But as Washington fans will see during tonight's game (7:30 p.m. WDCA-TV;20), any resemblance between that team and the one Holzman now directs ends with the uniform colors.

What Holzman has done with the Knicks seems so simple now, but in the last days of Reed's tenure there didn't appear to be any easy answers to correcting the team's woes. The personality conflicts, the inexperience and the lack of team coordination combined to defuse the squad's arsenal of talent.

Holzman, however, changed things with a few quick moves. What better way to help his young players than to slow down the pace and improve defense through patience? What better way to complement the youthful guards than to sign veteran holdout Earl Monroe? And what better way to solve the trouble at small forward spot than to start Toby Knight over a less agile, smaller Glen Gondrezick?

Now opponents are struggling to score 100 points against the Knicks, who were allowing 114 a game under Reed Holzman gradually is installing some of the basic plays that had made his old New York clubs so powerful, eliminating Reed's more helter-skelter approach. He made sense out of the substitutions, which had gone awry under Reed, and he began bringing out the talent of Spencer Haywood, who has been starting for the injured Bob McAdoo.

The result: a six-game winning streak right out of the blocks, then another win Saturday night to give New York a 13-9 record.

"Red's teams always play good defense, but one of the reasons for that," said Motta, "is his offense. He doesn't like to run that much so he'll play a deliberate brand of basketball. And that slows down the pace and keeps the score down.

Holzman is playing down his contributions to the Knicks' turnaround.

"I'm just doing what I've always done as a coach," he said. "We don't try to be fancy, just consistent. We've got the talent to be a good team."

He has plenty of quality players, starting with McAdoo, a former NBA scoring champ, and free agent Marvin Webster, who is off to a lackluster start since coming over from Seattle.

Add Haywood, the once-prolific scorer who never seemed to fit into Reed's scheme, and Monroe, the venerable guard who sat out the first part of the season because of a contract dispute. Then there are the promising youngsters: guards Ray Williams and Mike Richardson, the fourth man picked in June's draft, and forwards Knight and Gondreizck.

The sun is a club with quickness, height and firepower. Yet it was roaming so unchecked under Reed that turnovers and lackadasical play were as prevalent as baskets.

McAdoo, who has been bothered by a foot injury, has missed eight games and will not play tonight - The Bullets are only two victories off the club record winning streak of nine, set in 1968 - One reason Washington has been hard to beat in November: its starting front line is shooting better than 50 percent in the last 12 games; Wes Unseld is 45 fir 68 (66 percent) in the last 10 games.