Don Slaught's two-run double capped a six-run rally in the 11th inning and the Pittsburgh Pirates survived Andre Dawson's second grand slam in three days to stun the Chicago Cubs, 13-12, today.

In one of the most dramatic games of the 1,770 played between the two National League rivals since 1900, the Pirates came back from a 7-2 deficit to tie the score in the ninth and then overcame Dawson's slam in the 11th.

With Chicago leading, 12-7, Cubs reliever Heath Slocumb walked Jose Lind and Curtis Wilkerson and Orlando Merced singled to start the 11th, loading the bases with no outs and bringing on Mike Bielecki, the Cubs' sixth pitcher. Jay Bell doubled home two runs and Andy Van Slyke's sacrifice fly made the score 12-10.

Bobby Bonilla walked before Barry Bonds, who had struck out four times and was 1 for 26, singled to slice the Cubs' lead to one run. With one out and the bases loaded, Slaught hit a long drive over center fielder Jerome Walton's head to score Bonilla and Bonds standing up.