The upset, biggest so far at the combined WTA and ATP Masters event, took one hour, 49 minutes and marked the worst defeat five-time Grand Slam winner Sharapova has endured in Miami since she lost in the first round on her debut in 2003.
“It’s sport, and I happened to lose the match,” Sharapova said of dropping her second-round opener after a first-round bye. “Of course it’s a bit of a surprise … I’m expected to win.
“But that’s one of the reasons why we play the matches — you still have to go out and win it no matter if you’re the favorite.
“Today I didn’t,” added the former world number one, who has never lifted the trophy in Miami despite five trips to the final.
Gavrilova, who only broke into the top 100 on Monday, let out a squeal of delight upon sealing the win.
“I still can’t realize that it’s my dream,” said Gavrilova, who said she had dreamed of beating Sharapova ever since she saw her countrywoman beat Serena Williams in the Wimbledon final in 2004.
The surprise defeat of the second seed opens the door for a possible move by Romanian Simona Halep from number three to number two in the world rankings behind Williams.
– Too far behind –
Sharapova lost the opening set after nearly an hour and quickly found herself trailing the former junior world number one 4-1 in the second.
Sharapova clawed a break back but was then broken to love as Gavrilova set herself up for the win with a 5-3 lead.
She calmly closed out the biggest win of her career on her first match point.
“I thought I was very composed and just did my best,” Gavrilova said. “I was believing. When I sat down with my towel (at the end), I was crying a little bit.”
Sharapova said she simply left herself too much to do in the second set.
“I had little times where I did come back, but I was always behind,” said Sharapova, who was broken four times in the contest. “I put myself in a situation that was too far behind to come back from.”
Gavrilova lives and trains in Australia, where she is coached with funding from the Australian federation and is pursuing Australian citizenship.
The triumph was her first against a top-10 player after four prior chances. She had never before beaten anyone ranked higher than 35th.
Remaining women’s seeds fared better, with six of the top 16 making it through to the third round.
Number four Caroline Wozniacki lost just one game in a 6-0, 6-1 hammering of Madison Brengle, while Polish seventh seed Agnieszka Radwanska defeated Anna Schmiedlova 6-4, 7-5.
Eighth-seeded Russian Ekaterina Makarova, German ninth seed Andrea Petkovic, 12th-seeded Spaniard Carla Suarez Navarro, number 15 Karolina Pliskova of Czech Republic and 16th-seeded Venus Williams all advanced.
Williams, playing her first match since February 27, defeated Radwanska’s younger sister Urszula 6-3, 6-2 to set up a meeting with Australian Sam Stosur.
In men’s play, Canadian Vasek Pospisil spoiled Juan Martin del Potro’s return from injury with a 6-4, 7-6 (9/7) first-round win over the former US Open champion.
Argentina’s del Potro showed the rust after months of left wrist injury rehab in a contest lasting a shade under two hours.
The former world number four, who has slumped to 616 in the rankings, double-faulted on a set point which would have levelled the contest at a set each.
He saved one match point with an ace before succumbing with a service return long.
– Tennis without pain –
Del Potro, who had come back from right wrist surgery in 2010, underwent surgery on his left wrist last March.
He finished the 2014 season outside the top 100 for the first time since 2005 after contesting just four tournaments during the year.
Del Potro made an aborted comeback attempt in January before pulling out of the Australian Open because of pain in the wrist and underwent a second surgery two months ago.
Despite the defeat, he said he believes he’s heading in the right direction.
“I don’t feel frustrated, I have to take the positive things on my comeback,” del Potro said. “It doesn’t matter the score for now … I just wanted to play tennis and without pain.”