Perth - Canadian teenager Eugenie Bouchard swatted aside an out-of-sorts Serena Williams 6-2 6-1 at the Hopman Cup in Perth on Tuesday.
The American world number one's body language throughout the contest suggested she would rather have been anywhere else than on the blue hardcourts in Western Australia.
An on-court espresso helped spark her into life as she overcame a first set bagel to beat Italy's Flavia Pennetta 0-6 6-3 6-0 on Monday in the round robin mixed team event but nothing could help bring her out of Tuesday's malaise.
Sluggish footwork and uncharacteristically slow serves allowed Bouchard to break the 33-year-old with ease as the Canadian bounced back from a 6-0 6-4 thrashing by Czech Lucie Safarova in her opener.
Williams had complained of jet-lag following her previous day's efforts against Pennetta but she looked in good spirits as she teamed up with John Isner to win their mixed doubles against the Italians for a 3-0 whitewash later on Monday evening.
Williams, who did not call the trainer to court on Tuesday, showed flashes of her usual brilliance against Bouchard as she went for her shots but never had the consistency, or the fight, to beat the Canadian.
Whether it was jet-lag, illness or something else, Bouchard did not care as she notched a first win over the 18-times grand slam singles champion in the warm-up event for the year's first major, the Australian Open, later this month in Melbourne.
"I think I played pretty solid, I'm happy I came out and put on a better show than last time, the 19-year-old world number six said in a courtside interview.
Isner was next up against Vasek Pospisil before the quartet meet in the mixed doubles later on Tuesday.