Cueto (4-2) struck out eight and walked just two in picking up his third complete game and second shutout of the season. The right-hander has gone at least seven innings and allowed two or fewer runs in all nine of his starts this season, becoming the first pitcher since 1914 to accomplish that feat. He's tossed at least eight innings his last six trips to the mound.
His effort today dropped his league-leading ERA from 1.43 to 1.25.
Brandon Phillips contributed a three-run homer, ending 2-for-5, and Zack Cozart finished 3-for-4 with two RBI and a run scored for the Reds, who won for just the third time in seven games.
San Diego starting pitcher Ian Kennedy (2-5) suffered the loss, allowing five runs on 11 hits over six innings. He got off to a great start, striking out four and walking one, but hit a wall in the middle innings.
Kennedy matched Cueto's zeros through four innings, but ran into trouble with two outs in the fifth. With a runner on, Skip Schumaker singled to right to put runners on the corners for Phillips, who followed with a blast to left that cleared the wall for a 3-0 cushion.
Cueto, meanwhile, was cruising. After allowing a bunt single to Venable to start the game, he retired the next nine batters. Later, he retired eight in a row before allowing a Smith single with one out in the seventh.
Cueto ended the game by retiring eight of the last nine batters, as he faced just two over the minimum for the game. Venable walked with two outs in the ninth and became the first Padres runner to reach second when he advanced on a catcher's indifference.