We report an amplification-free thin-disk laser system delivering 0.9 GW peak power. The 120 fs pulses, at 14 MHz, centered around 1 µm, containing 12.8 µJ delivered by a thin-disk oscillator, were compressed by factor 15 down to 8.0 fs with 148 W average output power and overall 82% efficiency. Additionally, we showed that even a sub-two-cycle operation with 6.2 fs can be reached with this technology. The system will be a crucial part of the XUV frequency comb being developed and a unique high-repetition rate driver for attosecond pulse generation.