After taking a relatively drama-free opening set, 6-4, Jankovic started struggling with the tricky game of Vinci in the second set - a mix of powerful forehands and slice backhands, as well as strong volleying skills. After all, she is the No.1 doubles player in the world - and on her fifth set point Vinci finally converted, taking the second set in a nail-biting tie-break and pushing the quarterfinal to a third.
The No.15-seeded Vinci broke in the first game of the decider then held for 2-0 but the No.22-seeded Jankovic stepped it up from there, her rock solid ground game too sharp as she rattled off six of the next seven games, eventually wrapping up a 64 67(6) 63 win in exactly two and a half hours.
"I had some ups and downs in the match, but I'm very happy I managed to get through," Jankovic said. "In the first set I was down 2-0 and managed to come back and get the set. In the second set I was playing pretty well in a lot of games but was losing a lot of them, especially at the beginning when I went down 3-0 - I managed to come back but in the tie-break she played some really good points at the net. And in the third I was down again, 2-0, but thankfully I managed to get control in the end.
"Her game is difficult. It's tough to get underneath the ball when you play her. It was a difficult match and not an easy match at all for me, but again I'm happy to win and make the semifinals."
Jankovic has now won nine of her last 10 matches - she went 5-0 to win her first WTA title in three years at Bogotá, lost her opening match at Indian Wells and has now won her first four matches in Miami. And that loss in Indian Wells was a razor thin loss to Svetlana Kuznetsova, 06 62 75.
"I'm playing much better lately," Jankovic said. "I had a good showing in Bogotá and came to the US with a lot of confidence. I'm playing some good matches, I'm in good shape and I'm having fun."
Sharapova leads Jankovic in their head-to-head series, 6-1, though two of Sharapova's wins came via retirement and four of their five completed matches went three sets. This is their first meeting here.
"I really have nothing to lose," Jankovic said. "She's No.2 in the world and playing really well, so I just want to go out there and really enjoy my tennis, and hopefully play some good tennis tomorrow.
"Every match is a new match."