Robert Garrigus became the first player to be suspended for testing positive for "a drug of abuse" under the PGA Tour's Anti-Doping Programme.
The PGA Tour said in a statement that the American, who tweeted that he had failed a drugs test for marijuana, was suspended for three months.
Big-hitting Garrigus (41), who won on the PGA Tour in 2010 and finished third behind Rory McIlroy in the 2011 US Open, has spoken openly about his struggles with addiction, admitting to smoking marijuana during events with other Nationwide Tour players in 2002 before entering rehab the following year.
"After a long period of sobriety, I had a relapse and subsequently failed a drug test for marijuana,” Garrigus tweeted. "A drug, that although legal in many states, is not permitted under the PGA Tour’s anti-doping rules.”
He was not in action in the Valspar Championship in Florida, where defending champion Paul Casey carded a superb, five-under 66 to lead on six-under-par with Austin Cook, who shot 67.
Graeme McDowell made the one-over par cut on the mark when he got up and down for gutsy pars at the last two holes for a one-over 72 as Seamus Power bogeyed two of his last four and missed out one stroke after a 70.
The West Waterford man got back to level par or the tournament when eagled the par-five first (his 10th) from eight feet and birdied at the fourth and fifth.
But he then three-putted from long range for bogey at the sixth and dropped another shot at his final hole after a bunkered drive and approach, missing a nine footer for par.
Tied for 71st as the last few groups finished, he faced a nervous wait to see if the two-overs would make it and looked to have a chance when Sung Kang and Vaughn Taylor came to their final holes on one-over and were in danger or dropping shots.
He required just one of them to fail but Kang holed a 25 yard bunker shot for a birdie at the 18th and Taylor chipped to eight feet at the ninth and made the par putt to allow exactly 70 players to make the weekend on one-under. Scores
On the European Tour, Thomas Pieters fired a three-under 69 in testing conditions to take a one-stroke lead over Spain Nacho Elvira and Indonesia's Danny Masrin.
The big-hitting Belgian, who earned a 2016 Ryder Cup wildcard from Darren Clarke following his win in the Made in Denmark event, carded four birdies and a bogey in his second round at Saujana Golf and Country Club to lead on eight under par.
Pádraig Harrington (47) followed his opening 70 with a one-over 73 to share 43rd on one-under in his first start for four months with another veteran major winner, Ernie Els (49), just two shots off the lead after a 70.
Stephanie Meadow fired a five under 67 in the second round of the Bank of Hope Founders Cup to share 35th on five-under par, seven strokes behind China’s Yu Liu (64) and Korea’s Sung Hyun Park (66) at the Wildfire Golf Club at JW Marriott Phoenix Desert Ridge Resort & Spa. Scores
In amateur golf, Castlewarden's Lauren Walsh is tied for seventh heading into today's final round of the Italian Women's Amateur Championship in Sardinia. Scores
She shot a third round 74 to trail joint leaders Alessia Nobilio of Italy, and England's Lily May Humphreys by seven strokes on five-over at Is Molas.
Lurgan's Annabel Wilson fell back to joint 24th on 12-over after a 79 while Lisburn's Paula Grant also made the 54-hole cut, carding a 77 to lie tied 43rd on 233.
Holywood starlet Tom McKibbin also made the final round in the Italian Amateur Championship at Acaya Golf Club in Lecce. Scores
The Co Down star followed a pair of 77s with a 73 to lie joint 36th on 14-over, 16 strokes behind Germany's Brandon Dietzel.