Englishman Ian Poulter was beaten 8&6 by Kevin Kisner in the quarter-finals of the WGC Match Play after being told 10 minutes before he teed off he needed to win to qualify for the Masters.
The world number 64 had been told after winning his last-16 match that he had done enough to move into the top 50 and claim a spot in the year's first major.
The 42-year-old told BBC Sport: "I should never listen to other people.
"It's no excuse but it's disappointing to be given the wrong information."
Poulter had won his three matches in the round-robin section of the event before beating Louis Oosthuizen 2&1 in the last 16 earlier on Saturday.
He explained that after finishing that round, "the press and everyone" had told him he had done enough to qualify for the Masters at Augusta, which starts on Thursday, 5 April.
However, he said he was "disappointed" to receive a text message "to correct everybody and say we've made a mistake" 10 minutes before he was due to tee off against Kisner.
A clearly frustrated Poulter added that after beating Oosthuizen he tried to clarify his situation. "I asked three or four times 'are you sure are you sure are you sure?'" he said.
"'Yeah, yeah, you're definitely in.' No I'm not definitely in. So next time I won't listen to other people. I'll do my bit and focus better."
Poulter was off form as world number 36 Kisner went through to face Alex Noren.
The American found himself six up after registering three birdies before the turn as Poulter, normally a match play specialist, faded at the Austin Country Club.
"It was rubbish. I didn't give him any fight at all," said Poulter who moves up to 51st in the world.
He has one more chance, at next week's Houston Open, to secure his place at Augusta, although he is undecided if he will play the event in Texas.
"I'm tired, it's been a long, draining week," he said. "I'll wait until Monday night and if I haven't got the energy I won't play in Houston."
Kisner, who held a one-shot lead going into the final day at last year's PGA Championship before finishing in a share of seventh, is only the third player since 2014 to reach eight up in the tournament.
World number two Justin Thomas, who will replace Dustin Johnson at the top of the rankings if he wins the event, only needed two birdies to take a five-hole lead at the turn in his last 16 match with Korea's Kim Si-woo.
Having then made successive birdies and closed out a 6&5 win, the 24-year-old PGA champion, who has won all his matches this week, was one down to fellow American Kyle Stanley after five holes in the quarter-final, but made four birdies and secured victory at the 17th.
In Sunday's semi-finals, Thomas will play big-hitting compatriot Bubba Watson, who won five out of six holes on the back nine to beat Kiradech Aphibarnrat of Thailand in their quarter-final.
Earlier, Masters champion Sergio Garcia won the first hole of his last-16 match against Stanley but was three down at the turn. Although he reduced the deficit to one hole with two birdies, he bowed out at the 17th.
Englishman Tyrrell Hatton also departed at last-16 stage, despite winning the first two holes with birdies against Australian Cameron Smith.
World number 50 Smith won the next two holes and was three up by the 13th before securing victory by halving the par three 17th in birdie twos.
K Aphibarnrat (Tha) lost to B Watson (US) 5&3
J Thomas (US) beat K Stanley (US) 2&1
A Noren (Swe) beat C Smith (Aus) 4&2
K Kisner (US) beat I Poulter (Eng) 8&6
Last 16 results:
B Harman (US) lost to B Watson (US) 2&1
S Garcia (Spa) lost to K Stanley (US) 3&1
M Kuchar (US) lost to K Kisner (US) 1up
P Reed (US) lost to A Noren (Swe) 5&3
L Oosthuizen (SA) lost to I Poulter (Eng) 2&1
K Aphibarnrat (Tha) beat C Howell III (US) 1up
T Hatton (Eng) lost to C Smith (Aus) 2&1
J Thomas (US) beat Si-Woo Kim (Kor) 6&5
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