Adrian Peterson's unimaginable comeback story from major knee surgery continued Saturday when the Vikings running back joined Texans defensive end J.J. Watt as the only unanimous selections in the Associated Press' 2012 All-Pro voting.

Joining them on the first team with 42 of 50 possible votes was Vikings rookie kicker Blair Walsh, who went from making only 60 percent of his field goals (21 of 35) as a senior at Georgia to nailing 92.1 percent of them (35 of 38) with a league-record 10 50-yarders as an NFL rookie.

Two other Vikings -- fullback Jerome Felton and outside linebacker Chad Greenway -- made the second-team unit. Felton had 12 votes, finishing second to Baltimore's Vonta Leach (26). Greenway had only two votes, but it was enough to finish third at his position behind Denver's Von Miller (48) and Aldon Smith (47).

Center John Sullivan received seven votes to finish tied for third at his position behind Seattle's Max Unger (16) and Pittsburgh's Maurkice Pouncey (10). Other Vikings receiving votes at their respective positions were: defensive end Jared Allen (three) and offensive tackles Phil Loadholt (two) and Matt Kalil (one).

Meanwhile, at quarterback, Peyton Manning wasn't a surprise first-teamer. But his landslide victory was. He received 43 votes, while Green Bay's Aaron Rodgers (four) and New England's Tom Brady (three) split the other seven votes.

On the defensive side, voter confusion about how to handle 3-4 and 4-3 schemes surfaced again this year. A year after 49ers defensive end Justin Smith made first team at tackle and second team at end, Smith finished on the second team at both positions. He received 17 votes at tackle and six votes at end.

The AP ballot adds to the confusion because it asks for four defensive linemen (two tackles, two ends) and four linebackers (two outside, two inside).

Some voters obviously consider a 3-4 end -- which Smith is -- as a tackle in a 4-3 scheme. But Watt also is a 3-4 end, and he was a unanimous selection at end.

Peterson's unanimous selection wasn't a surprise, coming on the heels of a season that saw him rush for 2,097 yards, eight short of Eric Dickerson's NFL single-season record. But getting all 50 All-Pro voters to agree can't be assumed in any situation.

For instance, Lions receiver Calvin Johnson was left off one ballot after catching a league-high 122 passes for an NFL-record 1,964 yards (16.1 yards per catch).