Italy's Alessandro Petacchi won another stage in the Tour of Spain but Spaniard Roberto Heras, three times a previous race winner, had to battle back after crashing 40km out and injuring himself.

Heras, who rides for Liberty Seguros, badly cut his left knee but remounted, retaining his second place overall without losing time despite needing 15 stitches.

Russian Denis Menchov continues to lead, 47 seconds ahead of Heras and 1:53 clear of Francisco Mancebo.

Liberty Seguros media officer Jacinto Vidarte said of Heras: "The team doctors gave him the stitches in the team bus and he's now getting treatment for the wound."

The Spaniard is expected to start Friday's stage 13 but Dane Jakob Piil, also injured in the crash, has quit the race.

Petacchi notched his fourth stage win of this year's race in a bunch sprint, edging out German Erik Zabel and Italian Marco Zanotti.

Twice a winner in Burgos in previous Tours of Spain, Petacchi was also caught up in the Heras crash but with no serious consequences.

He told reporters: "We did ease the pace in the bunch until Heras returned."

Petacchi has won 16 Tour of Spain stages in his career and 39 stages on all major Tours.

Heras, seeking a record-breaking fourth overall win, will be hoping to shrug off Thursday's injury.

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