No British women reaching the Paris third round is a reality check after the euphoria of Boulter, Kartal and Raducanu winning their opening matches.
The trio were among the six British singles players who won in the first round – the biggest tally since 1973.
Like Raducanu, Boulter had the unenviable task of facing one of the world’s best players on Court Philippe Chatrier and the gulf between the pair was clear.
The 28-year-old started promisingly as she created four break points but, after being unable to convert, her momentum quickly disappeared and her serve began to break down.
Double faults handed over both of Keys’ breaks in the opening set, with another coming on break point in the first game of the second set.
Boulter’s second serve continued to buckle as she was broken again for 4-1 and, although she battled to recover it in the eighth game, she lost serve again as 30-year-old Keys secured victory with her second match point.
“It was a really tough match. I was a little bit off the mark,” said Boulter.
“Granted, she was hitting the ball pretty clean but I felt like I was just slightly off at the start.
“If I’d maybe got one of those breaks or held to go 2-2, it may have been a little bit easier for myself.”
Despite the disappointing nature of the defeat, Boulter will reflect positively on her clay-court season.
She dropped down to the second-tier of the WTA Tour and was rewarded with a maiden clay title in the French capital in the build-up to Roland Garros.
Playing on clay has never come easy to Boulter, who has struggled for fluidity and trust in her movement.
The way she was outclassed by Keys was a reminder of her inferior quality on the surface, but now can focus on the grass, where her serve and forehand can thrive.
