Baltimore's bullpen crew provided no relief for the 27,277 folks sweltering in 91-degree heat at Memorial Stadium tonight.

Bump Wills' grand slam, the only hit of the Rangers' five-run 10th inning, carried Texas to an 11-8 victory after the visitors had wiped out a 5-3 Oriole lead with three runs in the top of the ninth.

Dan Graham's two-out triple in the bottom half of the ninth tied the game, 6-6, and gave the Orioles another chance. It was not until Texas right fielder Billy Sample caught Graham's long drive with the bases loaded in the last of the 10th that the Rangers could stop sweating.

Baltimore's Sammy Stewart threw 39 pitches in the 10th inning and was warmly booed when he finally achieved the third out. As the Orioles took the field for the 10th, there was concern because numerous late lineup changes in a 20-player effort had put infielder Kiko Garcia in left field and catcher Graham in right.

But it turned out the empty bullpen was the disaster area, because Stewart had neither control nor hope or relief. He frittered the game away by hitting one batter and walking three others before Wills hit his third home run of the season, over the 387-foot marker in left center.

Wills had hardly celebrated before he became a raging protester, needing physical persuasion from Manager Pat Corrales before he left the presence of umpire John Shulock.

In their half of the 10th, the Orioles loaded the bases with one out on singles by Al Bumbry and Mark Belanger and a walk to Benny Ayala. After winning pitcher Danny Darwin fanned Lenn Sakata, Rick Dempsey hit a grounder to shortstop Dave Roberts, whose toss to second was snared by Wills after Wills had stepped across the base. Players were driftig in to congratulate Darwin when Shulock gave the safe sign, allowing a run to score. Wills then raced for Shulock and had to be pulled away.

When order was restored, Lee May singled to deep short, Roberts keeping the ball in the infield as another run scored, making it 11-8. It was then up to Graham, who had hit his triple off Darwin. Graham hit another shot to right, but he did not connect solidly and Sample was able to catch up with it.

Wills was smiling afterward. "I was excited about it (the grand slam), because it was my first one," he said, "and a lot of relatives from D.C. were here for the game and I'm happy for them, too.

"I don't get mad too often, but when I do I have a tendency to snap. I know that was an important out and I can honestly say -- if I didn't i'd admit it -- that I had my foot on the bag when the ball made contact with my glove."

Entering the ninth inning, the Orioles seemed headed for their fifth straight victory. Dave Ford, who relieved starter Scott McGregor in the sixth, had retired all seven Rangers he faced, with the aid of several radar-directed line drives.

Pinch hitter Pat Putnam started the ninth with a homerun into the rightfield bleachers, making it 5-4. Rusty Staub followed with an opposite-field double to left and Tim Stoddard came to Ford's rescue.

Jim Sundberg, after twice failing to bunt, grounded a game-tying single to right. Sundberg stole second and, after Pepe Frias sacrificed, lefty Tippy Martinez came in to pitch the lefty Mickey Rivers. Rivers drilled Martinez's first pitch to left to move the Rangers ahead, 6-5.

It was a walk to Rivers, on a 3-1 pitch with the bases loaded and two out, that restored the lead to Texas a 7-6 in the 10th. It was only the 13th walk of the year for Rivers, who said, "He was throwing low pitches. What am I gonna do, swing in the dirt?"

Wills then hit a breaking pitch that stayed up, and the Orioles' magic faced a stern test in the bottom of the 10th. Like the bullpen, it failed.