John Tudor pitched a two-hitter, scored two runs and was credited with the game-winning RBI as the St. Louis Cardinals, at home, protected their hold on first place in the East Division yesterday by defeating the Chicago Cubs, 7-0.

The Cubs lost their 12th straight and are one shy of the club record for consecutive losses, set in 1944 and again in 1982. The three-game series sweep in Busch Stadium built the Cardinals' record against the Cubs this year to 6-0, all in the past 10 days.

Tudor won his fifth straight after a 1-7 season start. He allowed only three base runners, one on a walk, and none made third base. He struck out six batters.

With one out in the St. Louis second inning, Ozzie Smith singled off Dick Ruthven (3-6). An out later, Tudor doubled the run home, then scored on Vince Coleman's single. Tudor singled to lead off the fourth. Coleman scored him with a triple and came in on Willie McGee's sacrifice fly to make it 4-0.

Doubles by Ivan DeJesus in the fifth and seventh, the latter for two RBI, helped increase the margin.

Tudor used only 82 pitches, but pointed out it was not as easy as it looked.

"I don't care what their record is," he said. "That's a good baseball team. We know that when it gets to be August or September, they'll be there."

The Cardinals have won 13 of their last 16, and "I don't think anybody wants to play us right now," first baseman Jack Clark said. "We know we've got a lot of home games coming up and we want to make the most of it."

St. Louis is home for 14 of 19 until the All-Star break.

Chicago Manager Jim Frey was philosophical.

"What can I say?" he asked. "Tudor pitched very well. We're not going to panic."