Triathlon: Alistair Brownlee ruled out of Madrid World Series event

Olympic champion Alistair Brownlee's hopes of regaining his world triathlon title have been hit by an ankle injury that has forced him to miss the World Series race in Madrid on Saturday.

The 25-year-old, world champion in 2009 and 2011, has only competed in one race this season, winning in San Diego but choosing to miss Auckland and Yokohama.

His injury is not thought serious and he should be fit for Kitzbuhel in July.

Brownlee lies joint 11th with his brother Jonny, the reigning champion.

The pair are more than 1,000 points behind Portuguese leader Joao Silva with five races left in the season, though the title is decided based on competitors' four best scores plus their score from the Grand Final.

Last year Alistair feared he might not make the Olympics because of an Achilles tear, but he recovered in time and went on to win gold.

He had been injury free this season and in April competed in a 10,000m race on the track in an attempt to qualify for the 2014 Commonwealth Games at the distance.

Olympic bronze-medallist Jonny struggled throughout the winter with an ankle problem that he initially feared would put him out for the season.

He will be competing in Madrid - a race he won last season on his way to his first world title - having triumphed on his first outing this season in Yokohama earlier in May.

Following July's event in Austria, the series moves on to Hamburg and Stockholm before the Grand Final over the Olympic course in London's Hyde Park in September.