â€śI am so happy for him,â€ť the West Ham manager told Radio 101. â€śMind you, he didnâ€™t even need that performance against Real Madrid to be considered one of the greatest in the world in his position.â€ť
Del Piero turns 34 on Sunday and won back-to-back Serie B and A Capocannoniere titles before the return to the Champions League.
Zola added: â€śDel Piero has always shown an immense strength of character every time he hit difficulties. For the past two years he has been playing at an extraordinary level.
â€śI am not surprised, because it is normal that after hitting 30 there is a period of adaptation to the new physical state.â€ť