ruthfulness in a sentence

1. Kafelnikov, the world No . 7, played the final set against Volkov with a ruthfulness that makes many people believe the 21-year-old is the newcomer most likely to challenge Agassi and Sampras.
2. Kafelnikov, the world No . 7, played the final set against Volkov with a ruthfulness that makes many people believe the 21-year-old is the newcomer most likely to challenge Agassi and Sampras'dominance at the top.
3. It's difficult to find ruthfulness in a sentence.