John Daly walked out of the Austrian Open in Atzenbrugg after a dispute over a two-shot penalty.
He stormed off at the 15th hole following a disagreement with officials over where his ball should have been dropped after a shot into the water.
The two-time major champion, nicknamed 'Wild Thing', also threw his club into the lake at the par-three 15th.
Tournament referee Andy McFee said: "I told him it was a two-shot penalty, at which point he said 'I'm done'."
The 45-year-old American was level par for the day and two over for the tournament before his troubles at the 15th, and was on course to make the cut.
McFee added: "If you play from a wrong place, and it's a serious breach then there could be a disqualification. But we always try to avoid this.
"When I knew it was not a serious breach I said 'You can carry on John'. But John did not want to do that."
Daly was playing with Spain's Miguel Angel Jimenez and Austria's Martin Wiegele at the Diamond Country Club outside Vienna, and had battled back to one over par with birdies at the 12th and 13th, before dropping a shot at the 14th.
Jimenez said: "I had tried to help him with the drop so I thought for a moment that maybe I had done something wrong. It definitely put me off for the remaining holes."
Wiegele added: "He [Daly] played some brilliant stuff but unfortunately it ended in a negative way. These two situations made him explode.
"He came to me and said that we were playing well and that he did not want to slow us down. He wished us both good luck for the weekend and left."
There is a four-way tie at the top of the leaderboard after two rounds. England's Robert Coles carded the best round of the day, a seven under par 65, to finish on seven under.
He shares the halfway lead with Dutchman Joost Luiten, Denmark's Thomas Norret, and India's Gaganjeet Bhullar. First-round leader Liam Bond of Wales dropped back to a share of ninth place after he shot a 74.
Only two of the world's top 100 are competing in Atzenbrugg - Jimenez lies in a tie for 18th after a second-round 69, while Ireland's three-time major winner Padraig Harrington is in a tie for 47th after he finished at one over.
Tom Lewis, who won the silver medal for finishing as top amateur at this year's Open, will earn a cheque in his first event as a professional after a round of 70 left him at level par and secured his place for the weekend.