Hoffman, who had opened with a scintillating 64, was two ahead with one hole to play but ran up a five at the par-four 18th after finding a bunker off the tee and failing to reach the green in two.
That left the three-time PGA Tour winner a stroke in front of compatriot Jamie Lovemark (68), with fellow Americans Chez Reavie (70) and Dustin Johnson (71) a further shot back at the Golf Club of Houston in Humble, Texas.
Welshman Jamie Donaldson and American Roberto Castro were also at eight under with three holes remaining when play was suspended for the day in fading light. Along with 25 other players, they will complete the second round on Saturday.
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World number two Spieth, looking to hone his game ahead of his title defence at next week's Masters, once again followed an impressive round with a mediocre one as he tagged a 73 to his opening 67 for 140.
The 22-year-old American mixed three birdies with four bogeys, three of them coming in his last seven holes, as he finished six strokes off the early pace.
"I'm close," Masters and U.S. Open champion Spieth told reporters about his overall form. "It's the dumb stuff, like two water balls on par-fives ... those holes are playing at 4.5 today and I played them with two sixes.
"There's four strokes right there, as well as two bogeys from 100 yards with wedges in my hand in the fairway this week. It's the kind of little things that are easy to shave off but it really stinks to keep on making those mistakes.
"I felt like I was hitting it very well at the start of the day. Everything seemed fine, then I made a mistake on three with my first putt and it just all kind of tumbled down from there."
Spieth won five PGA Tour titles last year, including two majors, but that consistent excellence has given way of late to a series of poor rounds that have sabotaged him.
Among his lowlights this season, the Texan has posted rounds of 76 (Valspar Championship), 79 (Northern Trust Open) and 74 (Pebble Beach Pro-Am).
The cut was projected to fall at one-under 143 as the second round spilled over into Saturday after play was delayed by 90 minutes earlier on Friday due to the threat of lightning.
(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Larry Fine/Nick Mulvenney)
