document: The American, 32, carded a first round two-under-par 70, leaving him four shots behind leader Francesco Molinari.
  The US Open champion withdrew on the first tee of the Masters first round, a day after falling on stairs in his rental home and hurting his lower back.
  "I hit the ball great, no issues," Johnson told reporters .
  "I just need to get some more rounds in, get some more reps, but I feel like the golf swing is in good shape.
  "If I hit it like I did on Thursday over the next few days, I will be right there on Sunday."
  Johnson, who was the only top-10 player in the field in North Carolina, is looking to become the first player since Tiger Woods in 2007-08 to secure four consecutive victories on the PGA Tour.
  He has already triumphed at the Genesis Open,WGC Mexico Championship and WGC Match Play this year.
  He added: "Since I had not played in so long I am happy with the way I played. I did not score that great, did not hole many putts. I felt like I hit good putts, just nothing was going in. All in all I am very pleased with the day."
  England's Greg Owen and Paul Casey are the highest-placed Britons on two under par, four shots off the lead.
  Johnson will aim to defend his US Open title at this year's tournament in Wisconsin, starting on 15 June.
summary: World number one Dustin Johnson "felt good physically" after making his return to competitive action at the Wells Fargo Championship.