Dwight Evans's sixth-inning grand slam and the overpowering relief pitching of Wes Gardner carried the Boston Red Sox to a 5-4 victory over the Texas Rangers yesterday, extending the Rangers's losing streak to six games.

Gardner, obtained in the 1985 trade that sent Bob Ojeda to the New York Mets, relieved winner Bruce Hurst (2-0) with men on second and third and none out in the seventh. He struck out Pete Incaviglia, Larry Parrish and Don Slaught on 14 pitches to end the threat and allowed just one hit while striking out seven in three innings.

Evan's hit came after the Rangers had taken a 4-1 lead with four runs in the fifth off Hurst, ending the lefthander's 1987 scoreless streak at 13 innings. Scott Fletcher and Incaviglia each had two-run singles in that rally.

But Ed Romero opened the Boston sixth with a single. Jim Rice was hit by a pitch with one out, and Don Baylor got a check-swing single to right, filling the bases.

Texas starter Charlie Hough threw two balls to Evans, then was replaced by Dale Mohorcic (1-1). Evans ran the count to 3-1, then lined his first homer of the year halfway up into the screen in left.

Gardner, who pitched just one inning last year because of shoulder surgery, came on after a walk and a dropped fly ball at the start of the seventh and went on to notch his first save.