Katie Boulter's grand slam struggles continued after she blew a one-set lead to suffer a shock defeat to little-known Argentinian rookie Solana Sierra in the second round of Wimbledon.
The British number two began the tournament in promising fashion by masterminding a statement three-set upset against ninth seed Paula Badosa.
But having gone from underdog to overwhelming favourite in the space of two days, she made another premature exit at a major after meekly going down 6-7 (7) 6-2 6-1 to 21-year-old Sierra.
World number 43 Boulter has never progressed beyond the third round at any of the four slams and for the second Wimbledon in a row she failed to make it that far.
Beaten by compatriot Harriet Dart at this stage 12 months ago, she struggled to find rhythm for much of an error-strewn Court One display.
Double faults from both players dogged a disjointed opening set during which Sierra caused problems with powerful ground strokes from the baseline.
Boulter served seven to her opponent's three but managed to temporarily set aside her troubles to come from 5-2 down to capitalise on her fourth set point in a tense tie-break.
The 28-year-old reacted by punching the air and letting out a roar of relief.
However, having dug herself out of a significant hole, she lost 10 of 11 games across sets two and three as lucky loser Sierra emphatically regained the initiative to progress in an hour and 53 minutes.
The world number 101 became the first Argentinian woman to reach round three of the Championships since Gisela Dulko in 2009.
"It feels amazing, I knew it was a really tough match, Katie is an amazing player," Sierra, who will face Spain's Cristina Bucsa next, said on court following her maiden tour-level victory over a top-50 player.
"I tried to focus on myself and enjoy the moment because it is a dream to play here in Wimbledon, on this court and with this crowd.
"From the beginning, I believed in myself that I could win this match, so I'm super happy."
