BALTIMORE, JULY 19 -- John Mitchell provided another much-needed quality start, Cal Ripken reached another milestone and Mickey Tettleton broke a 21-game home run drought tonight as the Baltimore Orioles beat the Chicago White Sox, 4-1, in front of 27,267 fans at Memorial Stadium.

Mitchell (2-2) gave up a run in the first when Robin Ventura doubled home Lance Johnson, but held the White Sox scoreless the rest of the way, giving up only five more singles before being lifted for Gregg Olson with two outs in the ninth.

Adam Peterson (0-2) went the distance and retired 16 of the last 17 batters he faced. But the Orioles touched him for three runs in the first inning and they proved enough as Mitchell kept the Red Sox in check.

Mitchell gave up a single to Carlton Fisk and a walk to Ron Kittle with two outs in the ninth, but Olson retired Scott Fletcher on a fly to center for his 21st save in 23 opportunities.

It was the third consecutive solid start for Mitchell, who has allowed only one homer in 53 1/3 innings. He pitched eight strong innings against the White Sox in Chicago on July 7 in gaining his first major league win since Aug. 5, 1987, when he was with the Mets. Sunday, he pitched 6 1/3 innings against the Twins, but got no decision.

"I don't know what my situation is permanently," said Mitchell, who has pitched at least into the seventh inning in five of his last six starts. "But I know I have to do good every time out."

Orioles Manager Frank Robinson scrapped his four-man rotation earlier this week in favor of a five-man cycle. Ben McDonald, the highly touted prospect and overall top pick in the June 1989 draft, was added to the rotation and will make his first major league start Saturday.

Meanwhile, the Cal Ripken milestone-a-game wagon continued to roll. Ripken handled four chances perfectly tonight for his 88th consecutive errorless game, tying the major league record for shortstops set by Kevin Elster of the New York Mets in 1988 and '89.

Ripken made his mark at bat too, hitting a two-run double in the first that came shortly after Phil Bradley's lead-off home run. Ripken's hit provided the winning margin in the Orioles' third victory in their last four games and eighth in their last 11.

The Orioles (43-48) are 6-3 since the all-star break and are 6 1/2 games behind AL East-leading Boston, which lost in Detroit tonight.

The White Sox (54-33) are two games behind Oakland in the AL West after losing on the road for only the fifth time in 27 games.

It took Chicago only two pitches to take a 1-0 lead in the top of the first, when Johnson blooped the game's first pitch into shallow center field for a hit and Ventura brought him home with a double to the right-center wall on the next pitch.

But the red-hot Bradley tied the game with a line-drive homer to left. It was Bradley's third homer and 10th RBI in eight games since coming off the disabled list following surgery on his left wrist.

The Orioles weren't done. After Joe Orsulak singled up the middle and Randy Milligan drew his major league-leading 78th walk, Ripken doubled down the right field line, scoring Orsulak and Milligan.

Tettleton's third-inning bash -- his 12th -- came on a two-out, full-count pitch; it was the first homer since June 23 for the Orioles' 1989 leader in that category. He came into the game batting .167 in his previous 26 games.

Tettleton, who hit 26 homers and made the all-star team last year, has been taking batting practice with Robinson in an attempt to "get him to make more contact," said Robinson.

"All hitters are streak hitters," said Robinson. "But some are more streaky than others. For some guys, a slump may last two games or two at-bats, but with a guy like Mickey it might last two weeks."