A cyclist has been disqualified from the Dubai Tour after punching race leader Marcel Kittel.
German sprinter Kittel, who rides for Quick-Step, was assaulted by Astana's Andrey Grivko during stage three of the event.
Kittel was left with a bleeding head during the midway stage of Thursday's event.
At the finish line, the 28-year-old told reporters that his injury had not come from a regular racing incident.
He said: "No, I didn't crash. I was punched by Grivko from Astana in my face. It was certainly not fair at all, and for sure it affected me."
He later added on Twitter: "I won't accept an apology for this. That has nothing to do with cycling. What Grivko did is a shame for our beautiful sport."
Kittel was seen in discussions with race officials throughout the stage and following the conclusion of the stage, it was announced that Grivko was disqualified because of the incident.
Exact details of the clash have not been confirmed, but other riders have claimed that Kittel was shouting at other competitors for dangerous riding before Grivko rode up alongside and punched him.
The violence does not come as a surprise to former Tour de France green jersey holder Robbie McEwen, who claimed on Twitter that he had also been hit by Grivko in the past.
He said: "Grivko fancies himself as a fighter. He hit me once during a stage at Eneco Tour about 10 yrs ago."
Despite the setback, Kittel maintained his eight second lead in the overall standings of the Dubai Tour.
His compatriot John Degenkolb of Trek-Segafredo claimed the individual stage win.