Angelique Kerber admitted to being caught cold as she had a battle to get past Claire Liu in three sets to progress to the third round of Wimbledon.
The 2016 finalist was staring a defeat in the face after losing the first set, but came back to win 3-6 6-2 6-4.
Liu has pedigree at the All England Club as she is the 2017 junior champion and Kerber concedes she did not know too much about her 18-year-old opponent.
She said: “I didn’t know a lot about her. This is always tough to play against someone you actually don’t know, and also don’t really know how she is playing.
“It was a quite tricky match. I was not playing my best today. I was not feeling my rhythm from the beginning. She played well. She had nothing to lose.
“For me it was just a match where I won. I’m just happy about that I won it at the end.”
Kerber will next meet Naomi Osaka in the third round after the Japanese beat British favourite Katie Boulter 6-3 6-4.
And Osaka is expecting a tough outing against the German.
She said: “I think she does a lot of things good. She runs really well. She returns really well. I can’t really say there’s anything she does bad.
“She was number one in the world and won two grand slams, so for sure she’s going to be a very hard opponent to play against.”
Ashleigh Barty came out on top in a clash of former Wimbledon junior champions with Eugenie Bouchard.
The Australian, who won the girls’ title in 2011, beat the 2012 champion 6-4
7-5 on Court Three to move into the third round.
Barty’s compatriot Daria Gavrilova won the all-Australian contest with Sam
Stosur 6-4 6-1 while Barbora Strycova beat Lesia Tsurenko 6-1 6-4 in matches
that were held over from Wednesday night.
There were also wins for 14th seed Daria Kasatkina, Carla Suarez Navarro and Katerina Siniakova.