Adam Schefter breaks down how the Vikings were able to acquire Sam Bradford from the Eagles. (1:39)

MINNEAPOLIS -- The Minnesota Vikings, who lost starting quarterback Teddy Bridgewater for the 2016 season with a severe left knee injury, acquired Sam Bradford in a trade with the Philadelphia Eagles on Saturday.

In return, the Eagles will receive the Vikings' first-round draft pick in 2017 as well as a conditional fourth-rounder in 2018.

If the Vikings reach the NFC Championship Game this season, the conditional fourth-round pick in 2018 will become a third-round pick, according to sources. If the Vikings win the Super Bowl, it will become a second-round pick.

The Vikings had inquired about Bradford after Bridgewater's injury earlier this week, sources told ESPN's Adam Caplan, but the Eagles were said to be happy with Bradford's progress this preseason. Talks picked up Friday, but even by Saturday morning, Bradford believed he'd be in Philadelphia for the season.

"My initial reaction was surprise," Bradford said. "It's something I really didn't think was a possibility. It kind of caught me off guard, but I think after the surprise, I was quickly filled with excitement for a new chapter and the opportunity ahead of me."

General manager Rick Spielman said Thursday night he wouldn't mortgage the Vikings' future to acquire a quarterback who might be in Minnesota only for the 2016 season. On Saturday evening, though, Spielman said he believed he hadn't done that with the trade for Bradford, giving two reasons: With eight picks in the 2017 draft, including two in the third and fourth rounds, the Vikings still have the ability to move back into the first round next spring. And with Bridgewater's recovery potentially stretching near the beginning of the 2017 season, the Vikings liked that they'd have another option for 2017 in case Bridgewater wasn't ready.

"Mortgaging the future, to me, was asking for some of our younger players -- current Pro Bowlers or significant players on this roster," Spielman said. "That's where I said I would not mortgage the future, giving any of the young players that are currently on our roster up. I think everybody knows how we feel about Teddy, but to me, it was just too unique of an opportunity to bring in a caliber of player like Sam Bradford. Going into next year, we have two very talented quarterbacks."

In his only season with the Eagles, Sam Bradford threw for 3,725 yards -- the fourth-best single-season total in franchise history -- and 19 touchdowns. AP Photo/Chris Szagola

With Bradford's exit, first-round pick Carson Wentz is expected to be the Eagles' starter if he has sufficiently recovered from his rib injury, sources told ESPN. Wentz suffered a hairline rib fracture during the team's first preseason game Aug. 11 against the Tampa Bay Buccaneers and did not play in the final three preseason games.

The Eagles traded with the Cleveland Browns to move up and select Wentz at No. 2 overall in this year's draft.

Though the Eagles said they had planned to bring Wentz along slowly, Philadelphia's executive vice president of football operations, Howie Roseman, said Wentz's preparation has accelerated the timetable.

"Our interaction with him and our discussions with him, he's come a long way, even since we got him in April," Roseman said.

Roseman added that Eagles brass already felt Wentz would be ready to take over as the team's starter should the opportunity to trade Bradford arise.

"He's worked out the last couple of days before he came back to practice and just seeing him with his receivers and his ability to verbalize the play call and, really, his comfort level in that," Roseman said.

Despite the praise of Wentz's rapid maturation, Roseman said the Vikings' interest is what ultimately led to the move.

"This was not our blueprint; this was not part of the plan," he said. "But as we sit, we have to be flexible, and we have to be able to take advantage of opportunities that give us an opportunity to get where we want to be. Our organization has had a run of success at some point, but we are trying to get that trophy, and to do that, sometimes you've got to do things like this that aren't so easy to do the week before the season starts."

Bradford NFL Injury Timeline Year Injury Games Out 2011 High left ankle sprain 6 2013 Torn left ACL 9 2014 Torn left ACL 16 2015 Concussion;

Sprained shoulder 2

Chase Daniel is likely to begin the regular season as the Eagles' backup.

Bradford re-signed with the Eagles in March to a two-year, $35 million deal with $22 million fully guaranteed. The Eagles paid Bradford's $11 million signing bonus, a source told Caplan, but the Vikings are responsible for the rest of his contract -- $20 million in base salaries and a $4 million March 2017 roster bonus.

Bradford now will play for his sixth offensive coordinator, Norv Turner, in seven seasons. Vikings tight ends coach Pat Shurmur was Bradford's offensive coordinator with the Eagles last season and for two seasons (2009-10) with the Rams. Shurmur's input, Spielman said, played a major role in the Vikings' decision to trade for Bradford. Roseman gave Vikings director of sports medicine Eric Sugarman, who worked for the Eagles from 2000 to 2005, permission to speak directly with Philadelphia's medical staff, and Spielman said the Vikings felt comfortable with the health of Bradford, who has torn the ACL in his left knee twice.

Bradford, the first overall selection in the 2010 draft out of Oklahoma, has thrown for 14,790 yards, 78 touchdowns and 52 interceptions in 63 career games, all of which have been starts.

He will be reunited with former Sooners teammate Adrian Peterson, who was told of the trade before Saturday's Oklahoma-Houston game.

"I'm pumped," Peterson said.

The Vikings had four quarterbacks on their roster, but they waived undrafted rookies Joel Stave and Brad Sorensen, while putting second-year signal-caller Taylor Heinicke on the reserve/non-football injury list. Heinicke could be ready to practice in three weeks, league sources told ESPN, but would not be able to return for the first six weeks of the season.

Journeyman quarterback Shaun Hill had taken over as the starter after Bridgewater was placed on injured reserve Wednesday. Spielman would not say whether Hill or Bradford would start on Sept. 11 against the Tennessee Titans, but it's believed Hill -- who has been with the Vikings for two years after his 2014 season as Bradford's teammate in St. Louis -- has the edge to start the first game because of his familiarity with the offense. Bradford said he planned to immerse himself in the Vikings' playbook on Saturday evening, and if he doesn't start against the Titans, he could be ready for the Vikings' Sunday night home opener the following week against the Green Bay Packers.

ESPN's Adam Caplan, Adam Schefter, Dan Graziano and Jake Trotter contributed to this report.