Johanna Konta dropped two match points on Wednesday against Ekaterina Makarova, who ultimately took the match in a 5-7 7-6 6-3 victory.
The Briton ranked 4th in the world after reaching the semi-finals at Wimbledon this year, was on course to beat the Russian in straight sets but lost the tie-breaker in the second set to change the direction of the match.
After losing her serve early in the first set, Konta battled back to take the opener.
In the second, she sent a forehand long while serving for the win to allow Makarova back in the match. The Brit then failed to convert her second match point to allow the world no.42 to take the second set on the tie-break.
In the third set, both remained on serve until Makarova broke in the eighth game to go 5-3 up.
Konta successfully defended the first match point of the third set, but fluffed her lines with a long return on the second to hand victory to Makarova.
The Russian will play Lucie Safarova in the third round.