Two No. 1 pick quarterbacks a draft apart, Manning and Smith will meet Sunday in the NFC Championship game with a shot at the Super Bowl after each has faced immense scrutiny over the years while playing on opposite coasts.

Manning made his mark by winning the Super Bowl four years ago. Smith took a significant step toward finally silencing the skeptics - for the time being, anyway - by leading last week’s thrilling, last-second 36-32 victory over Drew Brees and the favored Saints in his a spectacular playoff debut.

Early on, there were the questions about whether Manning would ever become an elite NFL quarterback like the other big-time QBs in the family, including father, Archie.

It calmed down for a time once he won a title. Then, the criticism returned last season, when Manning threw 25 interceptions.

That’s when he boldly let it be known he should be in the same conversation as Patriots star Tom Brady and the rest of the NFL’s best lining up under center.

“I consider myself in that class,’’ Manning said in August.

Smith, drafted No. 1 from Utah in 2005 one year after Manning was the top pick out of Ole Miss, won’t begin to compare his situation out West to what Manning has endured.

“His is a little different. To be Peyton’s little brother, No. 1 pick, you go to New York with the Giants, obviously that’s a lot of pressure,’’ Smith said. “I don’t think anyone has been in the situation he has. Those are pretty unique circumstances. Your older brother is arguably the greatest quarterback ever and a lot of expectations on you and then you go to the big city like New York. I didn’t have to face those things.’’

Smith got booed by his home fans at some point in nearly every game at Candlestick Park in recent seasons before leading a remarkable turnaround this year under first-year NFL coach Jim Harbaugh. Smith has been benched and belittled by more than one of his coaches along the way.

Sunday’s game will mark the second time two No. 1 pick QBs will square off in the conference championship. Vinny Testaverde and John Elway met in the 1998 AFC Championship game.

Manning and Smith have their teams on a roll. Each led five fourth-quarter comebacks during the season, then Smith had another in last Saturday’s thriller in which he hit Vernon Davis from 14 yards for the winning TD with nine seconds left.

Manning threw for 330 yards and three touchdowns to stun the defending champion Packers last weekend at Lambeau Field.

San Francisco linebacker Patrick Willis has known Manning’s potential for years - since their one-year stint as college teammates in 2003, the last time Willis had a winning season.

“As a freshman, I thought he was the greatest quarterback ever,’’ Willis said. “That was the best season I’d ever had in football. To see the things that he’s done, he’s won a Super Bowl. That’s the biggest accomplishment that we all try to go for, to win that.’’

The 49ers forced five turnovers in beating the Saints, then watched Smith shine at the end. On top of his game in the biggest of moments, at last. This is the Alex Smith the 49ers drafted over Aaron Rodgers nearly seven years ago.

What a comeback road it’s been considering he has played for seven offensive coordinators in as many seasons, dealt with a shoulder injury that sidelined him, and faced two head coaches questioning his talent and toughness.

“You have to have thick skin,’’ said Young, who visited with Smith this week. “He’s been through quarterbacking hell where you have a different coordinator, different language,’’ said Young. “He was trying to describe it like learning French and then learning Spanish and learning Japanese and just learning every weird, new language and having to be held accountable without the support.

“And this year, all of a sudden, he gets all of the support and he feels like: ‘Geez, I feel like I’m doing less. I feel like it’s easier.’ But yet, now he’s doing remarkable things.’’

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Manning was back at practice yesterday after missing part of Wednesday’s workout with a stomach bug, which forced him to receive intravenous fluids. “I’m 100 percent,’’ Manning said after practice. “I had a full practice today, did everything, took every rep. I feel good.’’ . . . Giants back Ahmad Bradshaw missed practice for the second straight day with a foot injury, which is not surprising. He has practiced only one day a week since returning in early December from the injury . . . LB Mark Herzlich (ankle), DE Justin Tuck (shoulder), DE Osi Umenyiora (ankle/knee), and CB Corey Webster (hamstring) were limited at Giants practice . . . Niners tight end Delanie Walker returned to practice for the first time since breaking his left jaw in two places late in the regular season and hopes to be healthy enough to play Sunday.