But Sandman isn't the only one who will be calling it a night at the end of the season. While Rivera's impending retirement is about as set in stone as one can get aside from turning in the actual papers to the players union, we might be watching the final few weeks in the careers of three other players with excellent and possibly Hall of Fame-worthy resumes.
One is Jason Giambi, who is winding down his Major League days as a 42-year-old designated hitter for the Cleveland Indians after interviewing for the Colorado Rockies' managerial opening last offseason.
Giambi hasn't said this year will be his last, but all indications are pointing in that direction. He has a toddler at home and has seen his role diminish from the early days, when he was a swashbuckling perennial MVP candidate (and winner of the American League MVP Award in 2000) for the Oakland A's, to the middle of his career as a consistent run producer for the Yanks, and on to Colorado and the later stages of his career as a bench bat and clubhouse sage.
Now that it's just about over, let's take a look at the numbers. They're impressive.
After notching his 2,000th career hit earlier this week, Giambi is one of 14 players since 1916 to have 400 home runs, 1,300 walks, 1,400 RBIs, 2,000 hits and an on-base percentage better than .400.
Hall of Fame? Maybe not. And Giambi has an admission of performance-enhancing drug use attached to him. But he might get some consideration.
"It's been a long journey," Giambi said after getting hit No. 2,000. "With all the ups and downs and things I've gone through, it feels like 4,000. I'll definitely take it and I'll treasure it, for sure."
Giambi has 19 years in the bigs and still has some pop, even in these gray-haired days. He has eight homers and 29 RBIs in 172 at-bats for the Tribe. If he does hang 'em up, he'll retire with five All-Star Game appearances.
"It's been a long road," Giambi said prior to the season. "I've had the greatest time in the world."
In Colorado, the Rockies and their fans will likely be saying goodbye to one of their franchise stalwarts, Todd Helton.
The 40-year-old first baseman, who has been with the Rockies organization since being selected with the eighth overall pick in the 1995 First-Year Player Draft and breaking into the Majors two years later, has put together a great career marked by consistency at the plate, loyalty to franchise and community, and caring about his teammates.
Oh, and some sheer brilliance, too.
Entering Tuesday's games, Helton had 367 career home runs, 1,396 RBIs and a .317/.415/.540 slash line for a career OPS of .955. He made All-Star teams in five consecutive years from 2000-04, his prime seasons during which he won a National League battling title (.372 in 2000), four Silver Sluggers and three Gold Gloves while averaging more than 37 homers and 126 RBIs per year.
Helton has been slowed by back injuries for years and missed much of 2012 because of hip surgery. This year he's been enjoying every big hit and moment in the summer sun that comes his way.
"I'm just swinging hard, hoping for a sound, and every once in a while, I'm hearing it," he said recently.
Helton's Hall of Fame case will be an interesting one considering some writers will call into question the inflated numbers that came along with pre-humidor Coors Field during the first five years of his career.
But Helton's value as a member of the Rockies will never be questioned. Just ask his teammates.
"He has that knack of touching guys in different ways," said relief pitcher Matt Belisle, who has developed a deep friendship with Helton since joining the team in 2009. "The jokes, the pranks, giving credit when credit is due when you wouldn't expect it from him. ... That pat on the back comes out of right field, and it really makes you feel tremendous.
"He can keep it loose as well as anybody in the clubhouse that I've ever been with. He's been doing this for a good spell now. He's one of those guys that has it in all areas of the game."
And so does the last member on this list, Andy Pettitte. Again, the veteran left-hander, who is 41 years old and in his 18th season in the Major Leagues and second since his first "retirement," has not revealed his plans beyond this season. But it's possible that with his 250th career victory and first place on the Yankees' all-time strikeout list safely in the books, Pettitte will decide to really retire.
"Whenever I shut it down again, that is going to be it," Pettitte said when he re-upped with the Yanks last winter. "It wouldn't be smart for me to just say right now that I would never play next year. I just don't think that would be smart, because I have no idea."
If it is the end, what a career we'll remember. Pettitte made three All-Star teams, won 20 games in a season twice, has 255 career victories and counting, finished in the top 10 in Cy Young Award voting five times, and has won a record 19 postseason games.
And five World Series rings.
"I feel very blessed being able to play this game as long as I have," Pettitte said after winning his 250th game in Seattle earlier this year.
"To be able to be on this club, play with this team, play with so many great players, have Mo close out so many of these games -- it makes it so special because he's such a great friend."