Campbell is ranked 53rd in the world and was 20th in the US Ryder Cup standings
US captain Paul Azinger has picked Chad Campbell, Steve Stricker, Hunter Mahan and JB Holmes as his wildcards for this month's Ryder Cup contest with Europe.
Campbell is the only one of the quartet with previous Ryder Cup experience.
Holmes, who is from Kentucky and knows the host Valhalla course, is the only pick to have won an event this year.
Mahan is in despite saying players were "slaves" during tournament week while Stricker just missed out on automatic qualification for the team.
The quartet join Stewart Cink, Phil Mickelson, Kenny Perry, Jim Furyk, Anthony Kim, Ben Curtis, Justin Leonard and Boo Weekley in a US line-up that is without injured world number one Tiger Woods.
With the addition of Stricker, Mahan and Holmes, the American team features six rookies in all, with Kim, Curtis and Weekley also experiencing the event for the first time.
The European team finalised on Sunday features four rookies, who all qualified automatically - Graeme McDowell, Justin Rose, Soren Hansen and Oliver Wilson.
"I thought we rounded off this team with the best possible players at this time," said Azinger. "It really depended on how the players performed in the last four weeks.
We are going to be underdogs in this event
US Ryder Cup skipper Paul Azinger
"We're missing Tiger Woods, the greatest player on earth, which is a big blow to us but I really like my team.
"It will be unique to be in America on our home soil as underdogs but clearly, the European team is strong.
"I think it's one of the strongest teams I've ever seen them bring across here.
"I like the team that we have and I'm really confident with who we have but I think it's evident that Europe has a terrific match-play record and team track record and we are going to be underdogs in this event and I think it's okay to be the underdog.
"Somebody has to be the underdog and it's very rare that it's evenly matched."
Azinger, a veteran of four Ryder Cups, is aiming to lead the US to their first Ryder Cup victory since the win at Brookline in 1999.
He was named skipper in November last year and immediately revamped the selection, changing the number of wildcard picks from two to four.
And he then asked to delay his selections three weeks in the hope of allowing players to find some form.
However, of the last nine US Tour events the only two American winners were the little-known pair Chez Reavie and Parker McLachlin.
"It's been difficult and it was up for grabs last week," added Azinger. "I said all along I wanted to change the selection process and we did that.
"But unfortunately the last three weeks have seen three foreign winners and nobody really jumped off the page.
"But my desire was to find the four who were playing the best and most confident after the PGA. These guys are playing really, really well."
Campbell will make a third successive appearance, but he has only ever won one match and has dropped to 53rd in the world.
He finished tied for seventh in the Deutsche Bank Championship on Monday, but his two results before that were 65th and a missed cut.
Stricker, ranked eighth in the world, has been one of the steadiest players on the PGA Tour for the last three years but said he had suffered from self-imposed Ryder Cup pressure over the last month.
A four-time winner on the PGA Tour, the 41-year-old has posted five top-10s in 19 starts this season, including a play-off loss at the Mercedes-Benz Championship in January, and finished ninth in the US Ryder Cup standings and one place outside the automatic qualifiers.
The big-hitting Holmes, 26, claimed his second PGA title with victory in the FBR Open when he beat Mickelson in a play-off and Azinger said the world number 55 knows Valhalla "like the back of his hand".
Last month, Mahan talked about Ryder Cup players being used as "slaves" and hinted at possible boycotts in the future because the fun had been sucked out of it.
But Azinger had said he would pick Mahan after he apologised for the comments and has described the 26-year-old world number 37 as a "lion".
Campbell, Stricker, Mahan and Holmes beat US Open runner up Rocco Mediate, Scott Verplank, Woody Austin, Brandt Snedeker, Sean O'Hair and DJ Trahan in the race for the wildcard spots.
European captain Nick Faldo named his wildcards on Sunday, ignoring the claims of Colin Montgomerie and Darren Clarke and instead calling up Ian Poulter and Paul Casey.
Europe have won five of the last six in the biennial event, with this year's contest taking place from 19-21 September.
Ryder Cup comparisons by world rankings:
UNITED STATES 2. Phil Mickelson 8. Steve Stricker 9. Stewart Cink 13. Jim Furyk 15. Anthony Kim 17. Kenny Perry 23. Justin Leonard 33. Ben Curtis 35. Boo Weekley 37. Hunter Mahan 53. Chad Campbell 55. JB Holmes
EUROPE 4. Padraig Harrington (Ireland) 5. Sergio Garcia (Spain) 6. Henrik Stenson (Sweden) 12. Lee Westwood (GB) 14. Justin Rose (GB) 18. Miguel A. Jimenez (Spa) 21. Robert Karlsson (Sweden) 25. Ian Poulter (GB) 31. Graeme McDowell (GB) 36. Paul Casey (GB) 44. Soren Hansen (Denmark) 48. Oliver Wilson (GB)
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