Mike Brown, Boston's rookie right-hander from Vienna, Va., pitched a five-hitter in Fenway Park for his first big-league shutout, while Dwight Evans and Jim Rice stung the Mariners with consecutive homers and Tony Armas applied the coup de grace with a grand slam.

With their fifth consecutive victory and 10th in 12 games, the Red Sox (15-9) retained their half-game lead over Baltimore in the East.

Brown (2-2) walked three and struck out two. He and Manager Ralph Houk figured that this was the real Mike Brown surfacing.

"I'm here because I know what I can do," said Brown. "That's the way he pitched in spring training and that's why he won a job on this club," said Houk. "Last time they killed me; now it was my turn," Brown said.

In his previous three starts since he last won (April 13), one against the Mariners, he yielded 14 runs in the first two innings.

"Mike has pitched a lot better than his record indicates," Houk said. Pitching, long a Red Sox weakness, has blossomed; the staff earned run average is 3.64.

"I warmed up a little longer today," Brown said. "I tried to get a little looser. Then I tried to keep the ball down. I didn't have good stuff early, which is becoming a habit, but it got better as I went along . . . They hit my slider and sinker, but they kept it in the ballpark."

In the third inning off Bob Stoddard (2-4), Evans lined the ball high off the light tower in left for his fifth homer and Rice sent his sixth high into the screen in left-center.

In the seventh, second baseman Julio Cruz booted a would-be double-play grounder and Boston turned it into a five-run inning. Bill Caudill intentionally walked Rice to fill the bases, then served up Armas' fifth homer of 1983, fourth career grand slam.

"Tony is on the brink of breaking loose," said Hauk.