As impressive as Manning and Ryan were, two of last week's top three, Tom Brady and Aaron Rodgers, maintained their stellar form and remain prime contenders. However, young pretender Robert Griffin III saw his chances take a tumble after he struggled against the Pittsburgh Steelers.
Here is a list of updated NFL MVP odds after eight weeks, beginning with the NFL's leading rusher.
The Minnesota Vikings' promising start to the 2012 season is fast becoming a distant memory, but Adrian Peterson continues to dominate.
Peterson leads the NFL in rushing at the halfway point, having gained 775 yards on 151 carries. His 5.1-yard average is excellent, but it's his league-leading eight runs of 20 or more yards that really stand out.
Anyone who wondered if Peterson would be the same after his knee injury and subsequent surgery has received an emphatic answer. Peterson remains an outsider for the award though, and the Vikings' third loss of the season sees his odds take a hit.
The idea of a tight end scooping the award may seem far-fetched, but Rob Gronkowksi won't be easy to overlook if he can keep up his current pace.
After breaking pretty much every meaningful record for his position last season, Gronkowski continues to dominate defenses in 2012. He leads all tight ends in yards with 580 and is fourth in yards per catch average with 13.5.
Gronkowski is also tied for the NFL lead in scoring receptions with seven. He scored twice during the New England Patriots' demolition of the St. Louis Rams in London, a game in which he registered season-high tallies for receptions with eight and yards with 146.
The 23-year-old is on a pace to match last season's exploits, and that has to grant him some consideration, at least as a long shot, for MVP honours.
Robert Griffin III's odds naturally took a big tumble after he struggled to outrun the Pittsburgh Steelers' veteran defense.
Griffin suffered through easily the worst performance of his young career, registering a season-low 47.1 completion percentage. He also threw for a meagre 177 yards and gained only eight yards on six runs.
Griffin's odds are also hurt by the Redskins' dire-looking 3-5 record.
A zero-touchdown, one-interception performance on the road against the Dallas Cowboys naturally sees Eli Manning's odds take a steep dip from last week.
He threw for only 192 yards against Rob Ryan's defense, and his season rating of 89.1 and eight interceptions count heavily against the two-time Super Bowl winner. However, in typical Manning fashion, as ordinary as he looked at times in Dallas, Manning still led the New York Giants to another win in a big game.
His ability to get results in the clutch is Manning's best quality and means that the league's 11th-rated passer still can't be ignored in the race for its MVP award.
Three more touchdown passes in Week 8 see Matt Ryan back among the favourites for NFL MVP.
Ryan's performance on the road against the dysfunctional Philadelphia Eagles was more efficient than spectacular. However, there's no arguing with his numbers after eight weeks.
Ryan is the league's third-rated passer, and he has keyed the Atlanta Falcons' smooth transition from a smash-mouth running offense to one that stretches the field through the air.
Tom Brady was in imperious form at Wembley. He dismantled what had been a tough St. Louis Rams defense and was the only member of the New England Patriots' fast-paced offense that didn't look like he was in a hurry.
Brady delivered the ball quickly and precisely all game as part of a 304-yard, four-touchdown performance. Running the varied hurry-up attack, the Patriots favour demands a lot from Brady, and he is getting more dominant in the role each week.
The 2011 MVP and last week's front-runner has to share top spot this week. Aaron Rodgers has reasserted the Green Bay Packers' credentials as a force in the NFC, and although he wasn't at his best in Week 8, he still looks MVP-calibre.
He threw for only 186 yards against a plucky Jacksonville Jaguars defense. However, Rodgers still managed to complete two touchdown passes and lead the Packers to a third straight victory.
That's enough to keep him at the top of this list, but now he has some company as favourite for the MVP.
Two dominant performances in two weeks are enough to help Peyton Manning surpass brother Eli and old nemesis Brady in the race for the NFL MVP award.
By reminding everyone that the old magic is still intact, Manning has made the Denver Broncos legitimate AFC contenders and positioned himself as the league's highest-rated passer. In Week 8, he destroyed the woeful New Orleans Saints, throwing three touchdowns and accumulating 305 yards through the air.
Everything with Manning this season is a process, and he needs at least another week playing at this level to be the outright favourite for the award. However, nothing seems beyond the four-time winner at the moment.