Only a bogey at the last hole cost the Spaniard, who is at 11 under alongside Billy Hurley III at Congressional Country Club.
Jon Rahm, Billy Hurley share lead at Congressional
Jon Rahm continued his dream start on his professional debut, holding a share of the lead at the halfway mark of the Quicken Loans National.
Rahm, 21, received the silver medal for low amateur at the U.S. Open after finishing tied for 23rd.
He backed up his opening 64 with a four-under 67, mixing six birdies with two bogeys in Maryland.
Rahm was on track for the outright lead until he two-putted the last, but he remains in a good position heading into the weekend.
Hurley had just one bogey in his six-under 65 as he surged into contention.
Veteran Vijay Singh is also in the hunt, sitting at eight under and three shots off the lead after a 66.
Ernie Els, who at 46 is seven years younger than the Fijian, produced a two-under 69 to be in a tie for fourth.
Joining the South African are Webb Simpson (68), Bill Haas (69) and Harold Varner III (69).
World number six Rickie Fowler is lurking, a second-straight three-under 68 leaving him five shots off the lead.
Defending champion Troy Merritt was far less fortunate, missing the cut at one over.
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