McIlroy, who won the event in 2012, captured last month's British Open and the PGA Championship three weeks ago but was thwarted in a bid for a fourth consecutive victory last week when Mahan won at The Barclays to pass him in playoff points.
"Excited to be back here -- 2012 was a great year," McIlroy said. "I was in the middle of a great run like I am now.
"My frame of mind is very similar, very relaxed. I'm not really putting a lot of pressure on myself. My golf game feels a little more controlled than it did then. And I'm driving the ball as good as I ever have.
"You want to win every event you play. I don't think there's any point of trying to pace yourself that way. I'd much rather be first or second than third, fourth or fifth."
The playoff field was trimmed to 100 this week and only 70 will advance to next week's BMW Championship in Denver, where only 30 points leaders will advance to the season-ending Tour Championship.
The top five on the points list in the Atlanta finale can take the season crown by winning the tournament, but McIlroy said he would not try to pace himself in order to save his best for the end of the four-week playoff grind.
"You want to win every event you play," McIlroy said. "I don't think there's any point of trying to pace yourself that way. I'd much rather be first or second than third, fourth or fifth."
McIlroy wants to complete another item on his list of goals by taking home the playoff trophy.
"It's one of the only things in golf I haven't achieved. It would be great to win it," McIlroy said. "Apart from the money, I feel like I've played a lot of good golf this season and ... I'd like to give it the finish it should have."
Among those looking to leap into the top 70 and keep their chances for the $10 million (7.59 million euros) champion's bonus are England's Luke Donald, Ian Poulter and Paul Casey, Zimbabwe's Brendon de Jonge, New Zealand's Danny Lee, Fiji's Vijay Singh and Australian Geoff Ogilvy.
- Ryder Cup hopefuls on display -
American Brandt Snedeker, 71st in points, also hopes to play well enough to earn a Ryder Cup selection from Tom Watson, who makes his three captain's choices for the US roster on Tuesday, the day after the tournament concludes.
Mahan likely put himself into one of the open US Ryder Cup spots with last week's victory but Snedeker, Keegan Bradley and Webb Simpson are also figured to be prime candidates.
On the European side, it's the final weekend to make an impression upon captain Paul McGinley, the Irishman whose picks will also be made Tuesday.
Poulter, the hero of Europe's trophy-winning comeback two years ago at Medinah, and Donald would need captain's picks to make the European squad.
Italy's Francesco Molinari and Dutchman Joost Luiten are playing in the European Tour's Italian Open and also trying to make an impression on McGinley.
The final European Ryder Cup vacancy will be filled in Italy. Scotsman Stephen Gallacher needs a top-two finish to unseat Northern Ireland's Graeme McDowell from the final automatic qualifying berth.
Both the Ryder Cup and playoff points chace enliven the event, which Sweden's Henrik Stenson won last year on his way to taking the US PGA playoff crown.