LEXINGTON, Ky. (AP) — The Southeastern Conference's six-year streak of national championships could be in jeopardy.

And the SEC has expansion to thank for making it happen.

No. 9 Texas A&M and Missouri are making their presence felt since the SEC invited them into the fold.

The Aggies (8-2, 5-2 SEC) rolled into Tuscaloosa and knocked off defending champion Alabama 29-24 and now the SEC is by no means a lock to get into the BCS title game. The Tigers (5-5, 2-5) have beaten Kentucky and Tennessee, adding to the coaching chaos at those schools.

Auburn's Gene Chizik is one of several SEC coaches who aren't surprised by either school's impact. He said the signs were there even before they left the Big 12.

"If you go back to SEC media day and what I said there, I don't change one thing that I said then," said Chizik, a former Texas defensive coordinator who was also Iowa State's head coach. "No one's teaching (coach) Kevin Sumlin how to coach football; no one's teaching Texas A&M how to play or win; no one's teaching Texas A&M about tradition.

"Missouri's had their ups and downs this year at times but they're another good football team. (Coach) Gary (Pinkel) does a great job. ... They're here to compete and they're here to win championships just like the rest of them. That's why I said it was a good fit."

Actually, the Aggies have become quite comfortable in the SEC.

Texas A&M was picked to finish fifth in the seven-team SEC West and has raised a few eyebrows with just how well its playing.

"I don't think a lot of people expected Texas A&M to do what they're doing now," Tennessee wide receiver Justin Hunter said. "They've got a real good quarterback (Johnny Manziel), a freshman coming out and running the ball like he did and beating the No. 1 team. It's real exciting."

The Aggies are a game behind West-leading Alabama entering Saturday's contest against Sam Houston State. They are tied with the Crimson Tide for the league-lead in scoring at 36.3 points per game. Texas A&M stands alone in several other offensive categories, including rushing offense (236.3 yards), passing offense (295.6) and total yards (531.9).

Sumlin said his Aggies benefited from the disappointing close home losses to Florida (20-17) and LSU (24-19) and that knocked Texas A&M out of any national championship discussions.

"I think in a way we drew some confidence from those games because those were top-tier teams, not only in this league but in the country," Sumlin said. "We didn't have the offense available in the first part of the year that we do now."

Leading the way is redshirt freshman phenom Manziel, also known as "Johnny Football."

Manziel is second in SEC rushing (631 yards, eight touchdowns) and passing (1,917 yards, eight TDs, five interceptions).

"Obviously, he did a great job against us," Alabama coach Nick Saban said. "To a large degree some of those plays he was able to make made a huge difference in the game."

Missouri's transition into the SEC has been tougher.

The Tigers lost their first four SEC games, but their two conference victories have contributed to Kentucky's Joker Phillips being fired and are part of the reason why coach Derek Dooley's future at Tennessee is uncertain.

Missouri's first SEC victory on Oct. 27 was a 33-10 rout of Kentucky, which also entered the game winless. The Wildcats fired Phillips on Nov. 4.

The Tigers' victory Saturday at Tennessee (4-6, 0-6) might have sealed Dooley's fate.

After seeing Missouri firsthand and watching Texas A&M last weekend, Phillips believes both schools just came in prepared to compete in the SEC.

"It's a really tough, tough league," said Phillips, who will coach Kentucky's final two regular games. "All of them that are winning have quarterbacks. They don't have true freshmen quarterbacks, they have quarterbacks and I think that gives everybody a chance."

Still, the Aggies' success is unprecedented in the SEC.

The conference's only other expansion was 1991 when then-independent South Carolina and Arkansas left the Southwest Conference to join the SEC. Both struggled in their 1992 debuts: The Gamecocks finished 5-6 overall and 3-5 in the SEC; the Razorbacks were 3-7-1 and 3-4-1.

Some SEC coaches say Texas A&M's impact is good for the league.

They don't believe the Aggies' win at Alabama should cost the conference champion a shot at the national title — an argument based mainly on five SEC teams being ranked in the top nine and six in the top 12.

South Carolina's Steve Spurrier is one of those coaches.

He said one loss shouldn't hurt East champion Georgia (9-1, 7-1) or Alabama (9-1, 6-1), if the Tide can clinch the West with a win against Auburn. Spurrier said the strong conference schedule stacks up against the unbeaten records of Oregon, Kansas State and Notre Dame.

"Isn't that what the BCS is for, to sort of go by strength of schedule and all that?" Spurrier said this week.

LSU coach Les Miles agrees with Spurrier.

"Some teams do not play the style of schedule we play week in and week out in this conference," Miles said. "The team that stands on that podium (after the SEC championship game) should have a chance to play for the national championship."

Thanks to expansion, that's now out of the SEC's control.