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Maria Sharapova admits she took her foot off the gas as the Russian survived a scare to beat American Lauren Davis at the Australian Open.
Sharapova conceded only one game in the first and third sets but in between Davis levelled when she won the second-set tie-break.
The world number 103 was unable to carry her momentum into the decider, however, as Sharapova sealed a 6-1 6-7 (5/7) 6-0 win.
She said: "I felt like I made it a little bit more difficult than I should have. I was hitting the ball well, doing the right things to get in that position, then let up.
"In a grand slam environment against anyone you can't expect to get away with it, and I didn't in the second set.
"But overall I'm really happy with how I came out in the third and stepped up, considering it's been many weeks since I've been in that position. So I was happy with the way I finished."
Sharapova has been hampered by injuries for the best part of a year while a problem with her forearm disrupted preparations for the first major tournament of the season.
The five-time grand slam champion, however, looks to be finding her rhythm and she will now meet talented Swiss Belinda Bencic in the fourth round.
"She's an impressive player," Sharapova said.
"A newer generation that's already established herself in the past season, beaten a lot of top players.
"It's a tough fourth round. We haven't played against each other before, but I'm sure we'll be playing many times. It's great that we can start here."
If Sharapova wins she is in line to meet Serena Williams in the quarter-finals - and the American appears to be hitting form too after she despatched another Russian, Daria Kasatkina, 6-1 6-1.
Williams dropped just two points in seven service games and wrapped up victory in a brisk 44 minutes.
"I definitely think I played better," Williams said. "Everything I've been trying to work on was kind of clicking today."
The 21-time major champion now faces world number 58 Margarita Gasparyan, also from Russia, whom she beat in straight sets at Wimbledon last year.
"I thought she played really well at Wimbledon. She was fearless," Williams said.
"I think she qualified at Wimbledon so she's obviously made leaps and bounds since then, gained a lot of confidence. She's here to play well and win."