The rivalries have already heated up after one weekend of action in the 2015 Diamond Race which got under way at the IAAF Diamond League in Doha and Shanghai on May 15 and 17.

In the men's 400m, there was the much-anticipated rivalry between Kirani James and LaShawn Merritt.

The pair have had some memorable battles in recent years, and were expected to go head to head again in the Diamond Race this year.

However, Merritt will have some catching up to do after their opening encounter, with James a clear winner in Shanghai. With Merritt only able to finish third, the Grenadian already has a three-point lead over his rival.

Doha and Shanghai also saw a whole host of lesser-known athletes make an early mark in the Diamond Race points tables of their respective events.

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Cuba's Pedro Pablo Pichardo set an IAAF Diamond League record with his 18.06m triple jump in Doha.

Pichardo, along with Dawit Seyaum (1500m), Airine Palsyte (high jump) and Jasmin Stowers (100m hurdles), now top the Diamond Race standings for the first time ever.

Stowers also set an IAAF Diamond League record with her run of 12.35 in Doha.

There were four more surprising Diamond Race leaders after Shanghai.

It was also a good weekend for many of the bigger names.

Tianna Bartoletta (long jump), Sandra Perkovic (discus) and Allyson Felix (200m) all secured four points in Doha, the latter equalling the IAAF Diamond League record with her run of 21.98.

In Shanghai, Caterine Ibarguen (triple jump), Piotr Malachowski (discus), Kaliese Spencer (400m hurdles), Silas Kiplagat (1500m), Jairus Birech (3000m steeplechase), Eunice Sum (800m) and Alonso Edward (200m) all started their defences of their Diamond Race titles with a win.