Ben Johnson of Toronto won his third race in as many nights, edging Chidi Imoh of Nigeria tonight in the 55-meter sprint, and Marcus Sanders of Michigan State won designation as top competitor at the Sherbrooke International meet.

Sanders outran MSU teammate Elvis Forde by nearly two seconds in the second-fastest time ever for the 600 meters, 1 minute 16.18 seconds. Only Donato Sabia of Italy, 1:15.77 in 1984, has done better.

Johnson, who won a 50-yard dash Friday in Ottawa and the 55 meters Saturday in East Rutherford, N.J., got a fine start and went on to a time of 6.13 seconds, to 6.14 for Imoh, a University of Missouri student. Johnson ran a 6.05 Saturday in the Vitalis-U.S. Invitational.

"I wasn't running for a fast time here," said Johnson, the Jamaican-born 1985 Canadian male athlete of the year. "I just wanted to win."

Emmit King, who won the event the previous five years at Sherbrooke, was fifth in 6.34.

Mark McKoy of Toronto won the men's 55-meter hurdles in 7.08 seconds; Cecilia Branch of Ottawa the women's 55 hurdles in 7.80, and in the women's 55-meter sprint, Sheila Echols of Louisiana State University edged Angela Bailey of Toronto, 6.80 to 6.81.

In the women's 1,000 meters, Kirsty McDermott ran a tactical race in 2:40.59, easily outdistancing Diana Richburg's 2:42.00. McDermott beat the previous Canadian best of 2:41.22.

Other Canadian winners included Dave Campbell, 1,000 meters in 2:20.62; Charmaine Crooks, women's 400 in 53.13, and Renee Belanger, women's 600 in 1:30.43. Ireland's Ray Flynn won the 1,500 meters in 3:41.50.

Two world indoor bests toppled in Europe, meanwhile.

In Vienna, Thomas Schoenlebe of East Germany lowered the men's 400-meter mark to 45.41 seconds at the Austrian International championships. Schoenlebe, 20, broke the record of 45.56 set last year by Todd Bennett of England.

In Bacau, Romania, Liviu Giurgean sped to a 7.43 in the men's 60-meter hurdles at the national championships, beating the 7.48 set three years ago by Thomas Munkelt of East Germany.