RENO, Nev., May 17 -- Sharmba Mitchell did something tonight no other 140-pounder had accomplished: He put Ben Tackie on the canvas in the 11th round of their International Boxing Federation title elimination bout. The knockdown was the exclamation point on a dominating effort by Mitchell, who took a unanimous decision before a standing-room-only crowd of more than 2,900 at City Center Pavilion.

Mitchell, who not only showed his hallmark mobility but also the ability to withstand Tackie's strong right hand, won handily on all three judges' scorecards. But he was most pleased with the knockdown, the first of Tackie's career.

"Tackie is a tough fighter, and I'm proud of my effort," said Mitchell (52-3) of Takoma Park. "I'm proud of my effort. I'm proud of it because it was the first time he had ever been knocked down."

Now Mitchell is hoping for a rematch with champion Kostya Tszyu, who stopped Mitchell in a unification bout on Feb. 3, 2001. Following the loss to Tszyu, Mitchell had surgery on his left knee and did not fight for 13 months.

The win made him the mandatory IBF challenger to Tszyu, and Mitchell's representatives are scheduled to be in New York this week to discuss making the fight with Showtime, which aired tonight's bout.

"I'm glad I'm be the number one [contender]," said Mitchell, the former World Boxing Association champion. "If [a championship bout] comes, it comes. I know I'll be fighting for a title."

Mitchell, 32, looked to be in excellent condition, taking the attack to Tackie with a sharp left hand and using his quickness to his advantage. Tackie (24-4) kept pressing forward, and the left-handed Mitchell made his opponent from Accra, Ghana, pay dearly for the strategy.

Doctors after the fight said Tackie had a possible torn right rotator cuff. There was also severe bruising above Tackie's left eye, which took the brunt of Mitchell's marksman-like left hand.

"Everybody wants to say I don't have any punching power, but I'm the only one to knock Tackie down . . . and hurt him . . . hurt him bad in a couple of rounds," Mitchell said. "I have punching power, but I want to display it when I want to display it."

The 11th round was the most eventful of the fight, which was scored 119-108 by two judges and 118-109 by the third.

After a looping left sent Tackie to the mat with 1 minute 58 seconds left in the round, Mitchell, who was cut above the left eye in the fourth, appeared to slip. Referee Vic Drakulich immediately took Mitchell to the corner, where the cut was inspected and the fight was allowed to resume.

• ELSEWHERE: Paul Spadafora (36-0-1), outpunched most of the fight and never able to get any momentum going despite a vocal hometown crowd, and Leonard Dorin (20-0-1) fought to a draw in a lightweight title unification fight in Pittsburgh. . . .

In an NBC fight from Atlantic City, New York 130-pounder Tiger Martinez (20-2-1) had to be content with a draw instead of an upset victory in Atlantic City over favored Nate Campbell (23-1-1) of Jacksonville.