Victoria Azarenka says Romanian Monica Niculescu tries to make her opponents feel "miserable" on court.
And for a period during their Australian Open first round match the world No.1 Azarenka felt just that during her 6-1 6-4 win.
Azarenka was more frustrated with herself though, than with the unusual slice game Niculescu employs.
She held a 4-0 record over the Romanian but felt her game slip at one point in the second set, which prompted several outbursts.
"It was just kind of to bring me back into competition, because I felt like the first set was really flowing my way and everything was going well for me," Azarenka said.
"Then I kind of miss-hit a few shots and she got really competitive.
"I felt like I was on the practice court a little bit, letting go few things that I shouldn't.
"After that I just really had to pump myself up - from there I got back and I started to do the right things again."
Azarenka described Niculescu's game as "definitely unusual" but says she is used to it since their days playing as juniors.
"She actually plays a lot more spin balls than back then," she said. "It was all slice from both sides before.
"She's unusual and she tries to make you feel a little bit, you know, miserable on the court, like you don't know what to do, because every ball comes from different angles."
It doesn't always work, according to the defending champion.
"I was trying to execute my shots, not really worried about what she's going to bring out because sometimes I don't think she knows where she's going," she said.
Azarenka was forced to withdraw from the Brisbane International when a pedicure led to an infection in her toe.