Lex was not observing the event too closely, and was more focused on monitoring its success overall. It was for that reason that he did not recognize Tiffany, not to mention that she looked vastly different from when he last saw her.
The guests, however, could not take their eyes off her! She was ruthless, not in the sense that she was defeating every enemy she came across. Her staggering performance was throwing off all the bets people had placed! Some noticed that there was more to her attacks than the simple sonic booms, but even if they could discover the secret, it would not help them remedy the situation!
It was fortunate then that the battle entered a balanced phase. The pillagers' coordination was keeping them from suffering any more losses while the participants' extreme powers and skills saved them. Whichever side gave in first would suffer tremendously.