He was also inspired and motivated even if he was relatively unchallenged.
The tournament's defending champion shot up the leaderboard with a brilliantly managed, bogey-free, seven-under-par 64.
Haas' round matched the brilliant blue sky over Riviera Country Club and was three shots better than anyone else Saturday.
Haas started the day tied for ninth, four shots back, and finished looking back at the field. He stands at 12-under 201 through 54 holes, and the bad news for the field is he's getting better as the tournament moves along. Haas' 64 followed rounds of 70 and 67.
Luke Donald and Fredrik Jacobson are four shots back at 205. Donald shot a 70 Saturday while Jacobson shot a 72.
Phil Mickelson started play five shots back of co-leaders Sang-Moon Bae and Jacobson but sputtered like a prop plane on his way to a 72. He dropped to three under and nine behind Haas.
Mickelson, after a bogey on No. 18, was still the star of the rail outside the hilltop clubhouse, signing autographs as Haas passed him on his way to the scorer's room. Unless Mickelson has another 60 in his bag left over from the Phoenix Open, it's hard to see him making a Sunday run.
Haas played in overdrive on a day everyone else seemed stuck in neutral.
His 64 was being universally heralded on a day when warm weather turned Riviera's fairways loose and made the greens almost rock-hard.
"Bill shooting seven under is incredible out there," Simpson said.
Simpson said the back nine "reminded me of a U.S. Open, just the way the ball is releasing and the temperature got up."
That has some credibility, as Simpson is the reigning U.S. Open champion.
For the record, the only U.S. Open played at Riviera, in 1948, was won by Ben Hogan.
Haas and Simpson will have plenty of time to chat Sunday in an all-Atlantic Coast Conference final grouping of former Wake Forest Demon Deacons. They will be joined by Schwartzel, a member of Conference SA (South Africa).
Simpson missed Haas by a year in college, but the two players are close friends. Simpson said Haas acted as his big brother when he turned pro.
"He's really looked after me on tour," Simpson said.
Simpson will be looking three rungs up at Haas on the leaderboard ladder at the start of the final round. Sunday could be a walk-along coronation if Haas plays the way he did Saturday.
Simpson is banking on Riviera's increasing trickiness.