Roger Federer feels he must rise to another level ahead of his Australian Open third-round clash against Tomas Berdych.
The Swiss 17-time grand-slam champion progressed on Wednesday with a 7-5 6-3 7-6 (7-3) win over American qualifier Noah Rubin.
Federer holds a 16-6 win-loss record over Berdych, including victories in their past five meetings.
But the 35-year-old said he needed to get better ahead of taking on the Czech 10th seed, who has reached at least the quarter-finals at Melbourne Park for the past six years.
"I know I've got to lift my game a little bit," Federer said.
"But then again, I haven't seen Tomas play a lot, to be honest. I didn't see anything, basically."
Berdych has only played four sets at the year's first grand slam, with Italian Luca Vanni having retired in the first round.
The 2010 Wimbledon runner-up cruised past American Ryan Harrison 6-3 7-6 (8-6) 6-2 in the second.
Federer said: "I thought he was going to have a tougher time against Ryan, to be honest, because Ryan has been playing well recently again. And it's super early in the draw.
"The court plays fast, like I said. He's caused difficulties for me in the past on faster courts: Cincinnati, New York, Wimbledon, Olympics in Athens. I know what he's got. I don't need to tell you where he's beaten me.
"Then again, I've played him here, played him on many occasions, as well, when it went my way.
"I've just got to play on my terms and really be focused on my own service games to make sure I don't have any lapses there."