Petacchi has 21 stage victories to his name this season

Petacchi consigned Zabel to his fifth second place since the start of the race, with Spain's Pedro Horillo third.

It was Petacchi's fourth victory of the tour, but Spain's Roberto Heras kept the overall lead.

Earlier, American Olympic time trial champion Tyler Hamilton was forced to pull out of the race, suffering with an upset stomach.

Stage 13 results:

1. Alessandro Petacchi (Ita) Fassa Bortolo 4hrs 1min 55secs
2. Erik Zabel (Ger) T-Mobile same time
3. Pedro Horrillo (Spa) Quick.Step-Davitamon same time
4. Stuart O'Grady (Aus) Cofidis same time
5. Cristian Moreni (Ita) Alessio-Bianchi same time
6. Erki Putsep (Est) Ag2R Prevoyance same time
7. Eddy Mazzoleni (Ita) Saeco same time
8. Guido Trenti (US) Fassa Bortolo same time
9. Marco Zanotti (Ita) Vini Caldirola-Nobili Rubinetterie same time
10. Antonio Cruz (US) US Postal same time

Overall standings:

1. Roberto Heras (Spa) Liberty Seguros 48hrs 52mins 45secs
2. Francisco Mancebo (Spa) Illes Balears-Banesto @ 0:35secs
3. Alejandro Valverde (Spa) Comunidad Valenciana-Kelme @ 0:49
4. Isidro Nozal (Spa) Liberty Seguros @ 1:12
5. Floyd Landis (US) US Postal @ 2:19
6. Manuel Beltran (Spa) US Postal @ 2:40
7. Carlos Sastre (Spa) Team CSC @ 3:16
8. Santiago Perez (Spa) Phonak @ 4:22
9. Angel Gomez (Spa) Costa De Almeria-Paternina @ 5:07
10. David Blanco (Spa) CV-Kelme @ 6:12