The comparisons between Kathy Cummings and the young Chris Evert are inevitable. Both wear matching designer skirts and blouses and ribbons in their hair. Both rely on two-handed backhands and on the presence of their fathers at courtside. And both have a steely determination and quiet cool under pressure that make them winners.

Yesterday, in the semifinals of the USTA National Amateur Indoor Tennis Championships at the Crystal Racquet and Health Club, top-seeded Cummings needed all that Evert-like mental toughness to survive five set points and beat third-seeded Connie Yowell of Yale, 7-6 (13-11), 3-6, 6-4.

In the first-set tie breaker Cummings lost eight of her last 10 serves while she was breaking Yowell six of seven times. Set point came on a lob by Cummings over the head of the net-minding Yowell. Another lob broke Yowell's serve in the first game of the third set and a double fault did the same in game three to put Cummings ahead, 3-0.

"I've had a lot of experience in tough matches," said Cummings, who is ranked 84th in the world. "I think I can always come back and bear down harder on the important points. She hits the ball real well, and all I could do was slice it back on my forehand. I use the lob because I like to keep her guessing at the net."

Cummings will defend her title today against Jennifer Goodling of Rollins College, who defeated Joy Cummings of Princeton, 6-4, 6-4, yesterday. Trailing, 3-1, in the second set, Goodling, who was the top player on the boys team at Dallastown (Pa.) High School, rallied to take a crucial 4-3 advantage.

Unseeded upstart John Zahurak, 17, found another way to win in the men's division yesterday, edging eighth seed Roberto Saad of Argentina, 6-4, 2-6, 7-5, despite the failure of his usually top-flight serve-and-volley game. Even when the Calvert Hall of Baltimore senior led 5-2 in the opening set, it was only because of his baseline game. Each player had service breaks in the last set, but it was Zahurak who took advantage to reach the final.

The final pits Baltimore-area native Zahurak against Stanford freshman Danny Goldie of McLean, who defeated Zimbabwe's Phil Tuckniss, 3-6, 6-4, 6-3. Tuckness led, 4-2, in the second set, and seemingly had the match wrapped up when Goldie's passing shots began clicking. He won the next seven games to take command and advanced to the final, despite being seeded 14th.