By DERRICK GOOLD

McClatchy-Tribune

CHICAGO -- If there is a nice, round number that allows Cardinals ace Adam Wainwright to look back on those dogged days of August when even games he won felt awry and see how far he's come as October approaches, it happened Monday.

Hindsight is 20.

With seven shutout innings at Wrigley Field, Wainwright became only the third Cardinals pitcher in the past six decades to win 20 games for the second time in his career with the club. Jon Jay backed Wainwright with three RBIs and Matt Adams came out of sick bay to double, score, and drive in two during the Cardinals' 8-0 rout of the host Cubs. Wainwright (20-9) became the second pitcher in the National League to reach 20 wins this season, and that matches his career high from 2010 when he finished 20-11.

The win kept the Cardinals the 2 { games ahead of the Pittsburgh Pirates for the lead in the NL Central. The Pirates (85-71) kept the pressure on the Cardinals (88-69) with a 1-0 win in Atlanta. The Cardinals dropped their magic number to four for the division title.

With the second 20-win season of his career, Wainwright has accomplished something his mentor Chris Carpenter didn't and his forbears as staff ace Matt Morris and Bob Forsch didn't either. Wainwright is the first Cardinals' starter with two 20-win seasons in his career as a Cardinal since Joaquin Andujar had back-to-back 20-win seasons in 1984 and '85. Andujar and Bob Gibson, who had five 20-win seasons, are the only Cardinal starters with multiple 20-win seasons since 1950.

Wainwright joined the presumptive Cy Young Award-winner Clayton Kershaw and the immortal Bartolo Colon as the only active players with multiple 20-win seasons.

He is the only active pitcher in the NL Central with single 20-win season.

Wainwright took a one-hitter into the seventh inning, and was one out away from pressing it toward the eighth when the Cubs rapped two quick singles against him. That gave center fielder Arismendy Alcantara the Cubs' second at-bat of the game against Wainwright with a runner in scoring position. He predictably bounced into a groundout. Wainwright did that throughout the game. Anthony Rizzo doubled in the first inning. Wainwright coaxed a routine fly ball to end the inning. Luis Valbuena worked a leadoff walk in the fifth inning. Wainwright bookended a strike out of Alcantara with two fly balls to center field. Jay raced down one in left-center to rob extra bases.

The two singles in the seventh pushed Wainwright's pitch count up to 106 by the time he was through his seventh shutout inning. That erased his slim chance at going for the fourth shutout of the season -- a total that would double his previous career high.