David Goffin admits he has no idea how to go about beating Roger Federer when the pair meet in the last four of the ATP Finals on Saturday.
Goffin has lost his last six encounters with the 19-time grand slam champion and was hammered 6-1 6-2 when they last met in Basel, also on a hard court, only three weeks ago.
The Belgian came from behind to beat Dominic Thiem on Friday and clinch second place in the group but he was not optimistic about his chances against the Swiss.
"I've never found a key to beat Roger, honestly, I don't know what to do tomorrow," Goffin said.
"But I'm going to try something, something different, something that I've never done in the past. I will try to do my best to play a better match than in Basel, for sure."
Goffin mustered only two games on Wednesday against an inspired Grigor Dimitrov and he looked set for another thrashing when Thiem stormed ahead 3-0.
But this time Goffin fought back, claiming 12 out of the next 14 games at London's O2 Arena to win 6-4 6-1 in just an hour and 11 minutes.
"I was a little bit surprised how well he started the match," Goffin said. "But I knew that I have found the solution in the past. I knew with my return I can be really aggressive. I knew it was the key to come back.
"As soon as I came back at three-all with a good service game, I knew that he was struggling a little bit with his ground-strokes.
"He was hitting too hard maybe a little bit. He lost his timing in his backhands. He started to think about how to hit the ball."
Defeat for Thiem extends the talented 24-year-old's troubles on any surface but clay.
He has seven wins from 16 matches against top-10 opponents on the red sand but now only two from 18 on hard courts.