Jessica Pegula was knocked out of the WTA Finals with one group match still to play as she fell to a lacklustre straight-set defeat by Barbora Krejcikova.
Wimbledon champion Krejcikova won 6-3 6-3 against a below-par Pegula for her first victory at the season-ending tournament in Riyadh, Saudi Arabia.
In a performance devoid of any positive energy, Pegula struggled to cope with Krejcikova's huge serves and hit just four winners in a match lasting little more than an hour.
"I'm really pleased with the way I played today," said eighth seed Krejcikova. "I felt I had to play my best tennis.