The American, moved to tears in her post-match press conference, looked far from her best and was beaten in straight sets 6-3 6-2 in just over an hour.
Kenin, 22, had admitted to struggling with the pressure of being a champion and it showed – she made 22 unforced errors against the experienced Kanepi, who dominated throughout her assault.
“I obviously felt like I couldn’t find my rhythm. I was obviously too nervous,” said Kenin, who praised Kanepi’s performance.
“I’m not there 100% physically or mentally,” Kenin added. “My game, everything, I feel really bad. Obviously it’s not good. I just couldn’t handle the pressure. I’m obviously not used to this.”
Despite a decisive season last year – winning in Melbourne and reaching the Roland Garros final – nerves were a problem for Kenin.
Even after playing well in her first round victory, she said she struggled to deal with her emotions on the pitch.
Kenin’s exit comes just days after French player Gael Monfils was also visibly moved after being knocked out of the tournament. He also said he had struggled with outside pressure and poor form coming into this tournament after such a tough year.
If Kenin struggled with the weight of expectations on her, that shouldn’t take anything away from Estonian Kanepi, who hit 22 winners and truly deserved the win. She will now face Croatia’s Donna Vekic in the third round.
“I served really well today, I think it helped a lot,” said Kanepi, 35. “My game plan was to play aggressively as I usually do.”
Barty fights through
Elsewhere, world No.1 Ashleigh Barty progressed into the next round after beating compatriot Aussie Daria Gavrilova 6-1 7-6 (9-7).
Barty, who spent nearly a year off tour amid the pandemic, won his first-round draw without losing a single game, but suffered a much more severe test on Thursday.
After crossing the first set, Australian Barty was forced to make a tie-break to settle the game.
“I think it’s just trying to be the best I can be every day, no matter what level it is,” Barty said after the game.
“I just make sure I apply as best I can so that whatever the outcome, I can leave the field with my head held high.
“Obviously having 12 months off is a little rusty, but I’m certainly happy with how I’ve been able to fight over the past two weeks.”