Estonia's Kristjan Rosenberg is the surprise leader after the first day of decathlon action ©Getty Images

Estonia's Kristjan Rosenberg is the surprise leader after the first day of decathlon action at the International Association of Athletics Federations Combined Events Challenge in Italy.

Rosenberg is on course for a personal best tally as he sits top at the halfway stage of the competition in Lane on 4,230 points.

The Estonian leads 2015 European under-20 champion Jan Doležal of the Czech Republic, ranked 21st in the world, by 89 points heading into the second day in the South Tyrol town.

Belgium's Jean-Baptiste Nutte is third on 4,081 points.

Rosenberg began the day by winning his 100 metres heat in 11.05sec, the joint second-fastest time recorded across the six races.

He was eighth in his long jump group, recording a best effort of 7.16 metres, before he threw 14.59m in the shot put.

European under-20 champion Jan Doležal of the Czech Republic is second at the halfway stage ©Getty Images
European under-20 champion Jan Doležal of the Czech Republic is second at the halfway stage ©Getty Images

The Estonian, 13th in the decathlon at the 2016 European Championships, starred in the high jump as he produced the best effort of the competition with 2.10m.

He crossed the line in the third-fastest 400m time, stopping the clock at 48.87.

Athletes from the United States occupy the first three positions on the heptathlon leaderboard.

Annie Kunz leads the way on 3,595 points, eight in front of nearest challenger Riley Cooks.

Allison Reaser is third having scored 3,472 points across the first four events.