Cathy Johnston completed an impressive performance yesterday, beating Patty Sheehan by two strokes in winning the LPGA du Maurier Classic golf tournament in Kitchener, Ontario.

Johnston shot a final-round 71 to complete four rounds at 276, 16 under for the 6,415-yard course at the Westmount Golf and Country Club. Johnston, who had never before led a tournament, withstood a final-day surge by Sheehan, who had rallied over the last 18 holes to win the McDonald's Championship and Rochester International in June.

This time Sheehan managed to gain a share of the lead, only to have Johnston regain control with a birdie at the par-5 13th hole. Johnston led by two strokes when Sheehan bogeyed the 14th; Johnston made it three with a birdie at 15.

Johnston could have lost the title at the 18th when, holding a two-shot lead, she flubbed a chip shot from the rough. But a 30-foot par putt saved it.

Sheehan, who finished with a 69 for 278, birdied No. 16, then missed a 15-footer for birdie at 17 that would have reduced the lead to one shot with one hole left.

Beth Daniel shot a 70 to finish at 281, Liselotte Neumann of Sweden was at 282 after a 72 and Missie Berteotti (72) was at 283.

Greater Hartford Open: In Cromwell, Conn., Wayne Levi, twice a runner-up in this event, shot a 67 to beat Mark Calcavecchia and three others by two strokes.

Levi, who lost last year when Paul Azinger chipped in from 40 feet on the final hole, completed 72 holes at 267, 13 under par. He had five birdies and two bogeys in the final round in becoming the PGA Tour's first three-time winner this year. Levi, who hadn't won in five years, also won the Atlanta Golf Classic and the Western Open.

Calcavecchia, the defending British Open champion, appeared to take control with three straight birdies, getting to 14 under after a near eagle on 13. But he double-bogeyed the 17th when he put the ball in the water and then three-putted for bogey on 18.

Calcavecchia shot a final-round 67 to finish at 269 with Rocco Mediate (65), Brad Fabel (70) and Chris Perry (69).

French Open: Irishman Philip Walton parred the second playoff hole to defeat Bernhard Langer and win the $595,000 tournament in Chantilly, his first victory on the European Tour. Walton shot one under in the final round to finish at 275; Langer, of West Germany, shot 67.