Roger Federer insisted he had plenty to improve on after recovering from a set down to defeat qualifier Radu Albot in the second round of the Miami Open.
The former world number one triumphed 4-6, 7-5, 6-3 against the Moldovan, who had won his first ATP title at Delray Beach last month.
“I felt I was in two minds,” said Swiss veteran Federer.
“In the heat of the moment, I started forgetting stuff my coach told me.
"I felt all the important points, points that could have led to something interesting for me, I played poorly because I was in two minds.”
Elsewhere, number six seed Kevin Anderson sunk Jaume Munar 6-4, 3-6, 6-3, while Stefanos Tsitsipas defeated lucky loser Mackenzie McDonald 7-6, 6-1.
Three top-10 seeds were eliminated, those being Alexander Zverev, Marin Cilic and Karen Khachanov.
On the women's side, eight-time Miami winner Serena Williams withdrew ahead of her scheduled clash with Wang Qiang due to a knee injury.
World number one Naomi Osaka was surprised 4-6, 7-6, 6-3 by Taiwanese player Hsieh Su-wei.
“I knew it was going to be a tough match,” said Osaka.
“She was hitting down the line on balls when I was sure she would go cross-court.
"I definitely thought she was being unpredictable.”
Double Wimbledon champion Petra Kvitova progressed after seeing off Donna Vekic 6-4, 3-6, 6-4, while Angelique Kerber lost to wild card Bianca Andreescu 6-4, 4-6, 6-1.
Also going through were Kiki Bertens, Ashleigh Barty and Caroline Wozniacki.