As Mariano Rivera prepares to retire, the closer's farewell tour has become a central subplot to the season. Major League Baseball's all-time saves leader has been greeted warmly in each of his road stops, and the Yankees are planning a ceremony of their own to honor Rivera's illustrious career in September.

Rivera will be the last active player to regularly wear uniform No. 42, with the number having been retired throughout MLB in 1997 to honor the achievements of barrier-breaking great Jackie Robinson. During his 19-year big league career, Rivera has also chiseled his own mark on the number's legacy. In honor of Rivera and his contributions, MLB.com is commemorating 42 notable moments from Rivera's career -- the 42 Days of Mo.

Mariano Rivera has a knack for locking up milestones, even when they aren't his own.

Long before he established himself as the pre-eminent closer of all time, the Yankees icon helped then-teammate Roger Clemens set himself apart as one of baseball's all-time winningest starting pitchers.

By pitching a perfect ninth inning against the Cardinals at Yankee Stadium on June 13, 2003, Rivera helped secure Clemens' 300th career win. The powerful right-hander became the 21st pitcher to reach the illustrious plateau, and only three -- Greg Maddux, Tom Glavine and Randy Johnson -- have since reached the mark.

Clemens scattered two runs on six hits while striking out 10 in 6 2/3 innings against St. Louis, and Chris Hammond and Antonio Osuna followed to combine for 1 1/3 innings of scoreless relief. Rivera came in for the ninth and faced pinch-hitter Orlando Palmeiro, left fielder Kerry Robinson and leadoff man Miguel Cairo.

The trio would be no match for Rivera, who recorded his eighth save of the year by retiring them in order -- a strikeout looking, a groundout back to the mound and a groundout to first base. He needed just nine pitches as the Yankees completed a 5-2 win.

The Yankees went on to win 101 games that season, finishing first in the American League East and advancing to the World Series, where they lost to the Marlins in six games. Clemens went on to win a career total of 354 games, good for ninth all-time, while Rivera saved 40 games that year and is the all-time career leader.