Spain's Alvaro Martin won the men's 20km race walk to claim the first gold of the World Athletics Championships in Budapest on Saturday as a host of hot favourites negotiated their qualifying rounds.

The two-time European champion clocked 1hr 17min 32sec for the victory on the streets of the Hungarian capital in a fast race that saw five of the first six finishers break national records.

"I was fourth at the last Olympic Games, I missed the bronze which motivated me to work hard," Martin said.

"In Tokyo, I felt when I was in the fourth position that I could win a medal. Unfortunately, it did not happen and that is why this gold medal is next step towards the next Olympic Games" in Paris next year.

The race walk was delayed for two hours because of a heavy storm and the opening day's action at the National Athletics Centre was put back an hour. (AFP)