Dan Martin has withdrawn from the Vuelta a Espana following a crash on Friday's seventh stage.

The Garmin-Sharp rider, who has enjoyed a strong season which included a Tour de France stage win and victory in one-day classic Liege-Bastogne-Liege, suffered a blow to the head and pulled out prior to Saturday's eighth stage.

He will now recuperate before leading Ireland's bid for glory in the Road World Championships in Florence on 28 September.

Martin, nephew of 1987 world champion Stephen Roche, wrote on Twitter: "Nothing broken, but the most painful crash (I've) ever had.

"Sad to leave the Vuelta but can't race with these bids flying round my head.

"I hit a hole or rock in the road. Down I went."

Martin also criticised race officials for compromising on rider safety.

He added: "Stunned at UCI (International Cycling Union) commisaires lack of compassion. Should concentrate on rider safety and less on UCI fundraising."