BALTIMORE, AUG. 17 -- The battered, beleaguered Baltimore Orioles trudged home to the supposedly comforting surroundings of Memorial Stadium tonight, only to find the most unwelcome sight of the Oakland Athletics staring at them from across the field.

So the venue changed but the result remained the disheartening same for the Orioles, who endured their eighth loss in 11 games -- an 8-3 bullying by the A's here before 45,379 that produced the 20th win of the season for Oakland starter Bob Welch.

Welch's evening resembled his victory over Baltimore last week in Oakland. Again the right-hander began sluggishly but toughened as the game progessed. Tonight that approach yielded an eight-inning, nine-hit, three-run performance that made him the earliest 20-game winner in the major leagues in 17 years. Dennis Eckersley finished with a perfect ninth.

Welch is 20-4 in 26 outings, having captured his last four starts to become Oakland's sixth 20-game winner -- and second quickest, 10 days behind Vida Blue's 1971 rush. He has lost just twice since May 5, and his stellar season is the favorite topic of conversation for an A's club that's overflowing with Cy Young and most valuable player years in the making.

"He's done's a complete, outstanding job for us from the get-go," said Manager Tony La Russa, ejected in the fourth inning for arguing with home plate umpire Mark Johnson about a Jose Canseco strikeout. "He's done all you can ask."

Said A's catcher Ron Hassey: "He's battled all season. He gets down, but he hangs in there and just gets better as a game goes on. He's tough."

The Orioles offered only mild resistance after a two-run second inning fueled by a home run by Sam Horn and a run-scoring single by David Segui, recalled earlier in the day to replace injured first baseman Randy Milligan. Segui celebrated his return to the majors with two hits, but he had little company as Welch progressed unscathed until Cal Ripken's eighth-inning home run.

Baltimore returned home having scored but one run in the final 23 innings of its just-completed 3-6 western road trip, and 11 of the Orioles' 32 runs over their last 11 games came on one afternoon against California and Mark Langston.

"Being at home is only an advantage if you play well," Manager Frank Robinson said. "We've had {Welch} on the ropes a couple of times this year, and we haven't gotten to him. He's a smart pitcher. He does what he needs to do to keep his team in the ballgame."

Tonight began a stretch in which the Orioles will play 25 of 35 games at home, but they are only 26-27 here. They won 11 of the previous 13 games started by John Mitchell or Ben McDonald, but Mitchell's prosperity ended this evening as he allowed seven hits and seven runs in 4 2/3 innings. He failed suddenly during a seven-run A's fifth inning after holding Oakland to a single hit over the first four innings.

The Orioles dropped to 56-61 but remained seven games behind the Boston Red Sox in the American League East. McDonald, who won twice during the road trip, will try to halt the skid at least temporarily when he tries Saturday for his sixth victory in six major league starts.

The AL West-leading A's improved to 76-43 with their ninth win in 11 games and seventh victory in 10 meetings with the Orioles this season. Mark McGwire fueled the fifth-inning outburst with a three-run home run. Felix Jose had three of Oakland's 13 hits, while Carney Lansford and Dave Henderson had two apiece.

"We're in a rut now," Robinson said. "We're not doing the things you need to do to win games, especially against the world champs. They take advantage of any mistake you make."

The Orioles were appreciating the comforts of home, cruising along with a 2-0 lead and enjoying the early handiwork of Mitchell, when the A's struck quickly and ruthlessly in the fifth to take command. They sent 12 batters to the plate, rapping seven hits and using McGwire's homer to match their best inning of the season and take a 7-2 advantage.

Hassey and Jose began the uprising with singles on hanging curveballs, and Mike Gallego singled for Oakland's first run one out later. Mitchell (5-5) walked Rickey Henderson -- making his first start in eight days after suffering a strained hamstring against the Orioles last week -- and Lansford followed with a two-run single.

One out later, McGwire reached down for a low, 2-2 fastball from Mitchell and sent it high over the left field fence at the 376-foot sign for his 31st home run. It was the 11th Memorial Stadium homer for the Oakland first baseman in his 85th at-bat here; Wednesday he became the first player in major league history with 30 or more home runs in each of his first four full seasons.

"The way I was going tonight, there's no way I should give up as many runs as I did," Mitchell said. "The two high curves to start the inning were bad pitches, and the one to McGwire was a bad pitch I got too much over the plate."

Mitchell was finished after Canseco doubled, but the A's weren't. Curt Schilling came on to walk Hassey, and Jose produced an RBI single.

Welch struggled but managed to keep the Orioles at bay. He allowed two runs in the second on Horn's solo homer -- at the time, Baltimore's second home run in 98 innings -- and Segui's two-out, run-scoring single.

But he escaped jams in the fourth and fifth, getting a double play off the bat of Craig Worthington to end one threat and retiring the top of the Orioles order with two runners aboard to squelch the other. He breezed through relatively trouble-free innings in the sixth and seventh before serving up Ripken's 15th homer in the eighth.

"I had the kind of night I've been having all year," Welch said. "I didn't overpower anyone or anything, but I hung in there and gave our offense the opportunity to win the game with some runs."

Orioles Notes: Robinson said pitcher Jeff Ballard is likely to remain in bullpen for the rest of the season.