For a while it looked like Sharapova was finally going to break her losing streak against Williams - she came out serving big and smacking her huge groundstrokes into the corners to build a 4-1 lead.
But the No.1-seeded Williams would have none of it. She started to unleash her own big serves and groundstrokes - as well as her trademark ability to go from defense to offense at the drop of a hat - to steal that set, 6-4, and she eventually put the No.4-seeded Sharapova away in straights, 64 63.
Both players displayed some impressive power in the match, but the numbers showed why Williams came out on top - she was just about even in her winners-to-errors differential (21 to 22 - including eight aces to two double faults) while Sharapova was -14 (15 to 29 - no aces and five doubles).
"I think she started out strong," Williams said. "I made some unforced errors, and I had a lot of chances to be up first game, and then had some chances to hold serve and chances to break again. So I think I definitely let myself down in the first three games, and then she just started playing better.
"But when I'm not playing well, or when I'm feeling lower energy, I know I can do better. That's always a plus. Especially during a match, sometimes I feel like, 'Okay, well, you can take it up a level.'"
"Despite my results against her, I still look forward to playing against Serena, because you learn so much from that type of level that she produces," Sharapova said of Williams. "She's an incredible champion. That's the reason she's at the top. She's accomplished a lot. Her tennis speaks for itself."
And while she clearly thrives against Sharapova, she also thrives in Miami - she is now through to her ninth career final at the Sony Open Tennis, more than any other event in her career. Williams' next-best tournaments in terms of finals reached are Wimbledon and the US Open - seven finals at each.
"That's pretty awesome - I didn't even realize!" Williams said when she was told about the finals stat in her on-court interview. "But I just love playing here in Miami. This is my home. I love you guys!"
Williams leads Li in their head-to-head series, 10-1, and has won their last nine meetings.