The Swede got off to a tough start in Germany and ended up 0-1 down against Frenchman Alexis Lebrun.
But there was nothing that stopped the 28-year-old.
Anton Källberg won three straight sets and advanced to the quarterfinals with a 3–1 score.
"I am of course super happy and lucky to be able to play this well in another match," he says in the victory interview on SVT's broadcast.
But I'm also completely exhausted. It was a tough match against Alexis.
In the quarterfinals – which will be played on Saturday – Källberg expects another difficult match in Frankfurt.
Then the home player Dang Qiu will be waiting.
We know each other very well and have played together on the club team for several years, so we have trained a lot together, he says.
It's a tough opponent for me and I think I've lost the last few times we've met. I need to be as good as I was in this match, or even a little better.
Earlier during the WTT tournament, Anton Källberg won against compatriot Truls Möregårdh 3–0 in sets – a match that lasted just over 18 minutes.
