MIAMI, FL, USA - Reigning Miami Open champion Sloane Stephens saw her title defense ended by Tatjana Maria in the third round on Sunday, 6-3, 6-2.

The win is Maria's third against a Top 10 player in her career, and first since she defeated Elina Svitolina at Wimbledon nearly a year ago.

Two of the German's Top 10 scalps have come in Miami, as she scored her first victory against then-World No.7 Eugenie Bouchard at the event in 2015, 6-0, 7-6(4).

"I could not be happier right now," Maria said on-court after the match. "I think I played at home, because I live here. It was helping me a lot. My family, everybody's here, my friends and I think it helps.

"My game is pretty special, so I knew that tonight I had a chance. I played two times against Sloane, so I knew what to expect."

The result was a complete reversal of the pair's last meeting, won by Stephens last summer in Cincinnati by identical set scores, as the German used her variety to finish several points at net, and lured the 2017 US Open champion into 37 unforced errors in the match.

"I think from every match you learn something. For sure, it was helping me that I played her already twice," the German added.

"I was happy today that I could really find my game and that I was not too passive and I could change the rhythm. It was working out well."

Despite landing just 42 percent of her first serves for the match, Maria won 68 percent of the points played behnd them and broke Stephens five times to seal the win.

The German needed four match points to seal victory, which included a dramatic moment in the final game where she thought she won the match.

Maria prematurely celebrated a forehand passing shot, only to see the ball called out and confirmed on Hawk-Eye review. 

"It was horrible, because you think it's over, but it's not, so I said to myself, 'Okay it doesn't matter, start again from the beginning,'" Maria said with a laugh to reporters.

"It was helping me a little bit to regroup right away, and I was so happy at the end that it was really done."

Up next for Maria will be Czech teenager Marketa Vondrousova, who scored a victory over No.16 seed and Doha champion Elise Mertens earlier on Sunday.

"I know she's a lefty. She's been playing pretty good. She had a lot of wins in Indian Wells and also in Miami again. She's a young player," Maria said.

"We never played each other, never practiced with each other so it's something new, but first I will enjoy this win."

The American now turns her attention to the clay court season, closing the book on the first three months of the year in which she only won consecutive matches once, en route to a fourth-round showing at the Australian Open.

"I just played a bad match and she played well, and that's never a good combo," Stephens said in defeat.

"She's a great player, she plays with a lot of variations and she's a tricky opponent. She just played the better match today.

"I'm looking forward to getting back on the clay, my favorite surface. Hopefully, I can get some momentum and try to play some good tennis in the clay court season."