The top seed and world No 1 made only one birdie to halve the first, but he was then content to grind out the pars as Dufner made a string of mistakes to gift McIlroy a comfortable 5&4 win.
The new round-robin group format at TPC Harding Park in San Francisco spared Dufner an early flight home, while McIlroy will expect tougher tests against Group 1 rivals Brandt Snedeker on Thursday and reigning FedExCup champion Billy Horschel on Friday.
“I felt like tee to green I played pretty well,” McIlroy told Sky Sports 4.??”I didn’t hole many putts and felt that the green speeds were pretty??inconsistent, but did what I needed to do and we move on to tomorrow.
???It’s good to win that first match. Luckily I’ve done that and the mindset going into tomorrow is I have to win, you have to win every match. There???s no point in thinking you can’t win matches and progress here.
“I need to hole a few more putts. Jason didn’t have his best stuff, obviously, so I just tried to put him under pressure from the start, tried to hit fairways, hit greens, and try and make him force a little bit. In match play, you just need to beat the person that’s in front of you and I did that today.???
But Masters champion Jordan Spieth clearly found the course to his liking, and the world No 2 was an approximate six under par in his convincing 4&2 win over debutant Mikko Ilonen.
The Finn, who won the Volvo World Match Play Championship at the London Club last October, was the last man to get into the field after Phil Mickelson’s withdrawal.
Spieth reeled off three birdies in four holes from the fifth, but Ilonen hit back with birdies at nine and 11 to reduce the deficit to one before the young Texan won the next two holes and wrapped up victory on the 16th.
“It’s good to get off to a good start. I played solid golf today,” Spieth said. “It got a little interesting there on the back nine but a big turnaround on 12 and 13 to get three up and close it out on 16. I’m extremely pleased.”
But third seed Henrik Stenson paid the price for missing a four-foot putt for the match on 17 as he slipped to defeat to John Senden at the first extra hole.
Zurich Classic of New Orleans winner Justin Rose also suffered a surprise 3&2 loss to Marc Leishman in the opening match of the tournament, while defending champion and world No 7 Jason Day crashed to a 4&3 defeat to Charley Hoffman.
Jimmy Walker was edged out by compatriot Gary Woodland at the 19th, while Francesco Molinari pulled off one of the biggest wins of his career as he cruised to a 5&4 win over Adam Scott.
Ben Martin provided the highlight of the first day, firing a superb hole-in-one at the 230-yard 17th before closing out a 1up victory over 14th seed Matt Kuchar.