LOS ANGELES -- Only 21 defensive tackles have been named first-team All-Pro by the Associated Press on at least three occasions.

Two of them now play for the Los Angeles Rams.

When Ndamukong Suh signed a one-year, $14 million contract to join the team that employs Aaron Donald, he didn't just form what might be the game's most menacing pass rush; he became half of a duo that might turn out to be unrivaled throughout NFL history.

With Ndamukong Suh joining Aaron Donald, the Rams' pass rush will be the first of its kind. AP Photo/Wilfredo Lee

Suh and Donald have combined for six All-Pro selections. In no other instance have two defensive tackles with at least three All-Pro selections each been teammates, at any point in their careers. There have been six instances when two defensive tackles with at least two first-team All-Pros resided on the same team, but only two of those duos were part of the same defensive line after they had already accomplished that feat.

In other words, comps for the Suh-Donald pairing are a rare find.

There were potentially great ones that were painstakingly close to forming but didn't. Bob Lilly retired the year before the Dallas Cowboys drafted Randy White in 1975. Charlie Johnson's last season came right before the Minnesota Vikings selected Keith Millard in 1985. Cortez Kennedy hung them up right before John Randle joined the Seattle Seahawks in 2001. And Suh -- set to be introduced by the Rams on Thursday morning -- officially left the Detroit Lions two days before they traded for Haloti Ngata.

Now he forms an even greater pairing, and we tried to come up with similar ones:

Alex Karras and Roger Brown: Brown is involved in the only two defensive-tackle pairings that involved each member already being named first-team All-Pro at least twice. The other took place with Merlin Olsen for the Rams from 1967-69. But this one with Karras lasted longer, from 1960-66, for the Lions. It encompassed Brown's first seven seasons, which saw him get invited to five Pro Bowls. Karras -- also a professional wrestler and actor -- was invited to four of them during that time, even though he missed an entire season serving a gambling suspension. The Lions never made the playoffs with them as teammates; this would become a theme.

Rosey Grier and Olsen: While Karras and Brown were doing their thing along the interior in Detroit, Grier and Olsen were doing it in L.A. The two were teammates from 1963-66, the early stages of a devastating defensive line that would eventually be called "The Fearsome Foursome." Olsen, one of the greatest defensive tackles ever, spent all 15 of his Hall of Fame seasons with the Rams, making the Pro Bowl in all but one of them. His second, third, fourth and fifth year -- from 1963 to 1966 -- came alongside Grier, a two-time Pro Bowler who joined him after seven seasons with the New York Giants. The Rams won only 22 of 56 games with Grier and Olsen, but it surely wasn't on them.

William Perry and Steve McMichael: Perry, whose massive frame made him "The Fridge," soaked up most of the fame. But McMichael was a steady contributor for Chicago Bears teams throughout the 1980s, one of which won it all behind one of the most dominant defenses ever. That 1985 Super Bowl-winning season was Perry's first. He and McMichael were teammates for eight full seasons, six of which saw the Bears reach the playoffs. Perry and McMichael combined for 94 sacks from 1985-92, and 65.5 of them came from McMichael, a two-time All-Pro (and, strangely, another professional wrestler on this list). Their combined weight topped 600 pounds, in case you're wondering.