The Dutch men and Australian women are both chasing their third golds in a row in the Olympic hockey tournament, but all the teams agree the field is wide open and the titles are anyone's for the taking.

In the men's competition, which starts on Sunday, world champions and top-ranked Germany are the most feared team as they battle for their first medal since winning gold in 1992.

The Dutch are well primed to defend their title with world player of the year Teun de Nooijer and corner specialist Taeke Taekema leading the pack but others also reckon they have a chance to climb on to the podium.

"This is the most open hockey Olympics ever. There are seven or eight teams with a good chance and the lesser ranked boys could cause an upset. You don't have to be the best to win," said British coach Jason Lee after a warm-up match.

While hockey used to be a game of flowing stickwork, dominated by India in the mid-20th century, many goals now come from penalty-corners, where a new rule could cause confusion.

In June, the International Hockey Federation ruled that players could no longer charge into the line of a penalty flick with the intention of stopping the ball with their bodies.

That should play to the advantage of players like Taekema and Pakistan's Sohail Abbas, considered the best flicker around.

"We have a great weapon in Sohail but we have to get into the right battle lines to use him. Getting penalties depends on us, our opponents, the umpires. It's not easy," said Pakistan coach Roelant Oltmans.

Good fights should also be set by Australia, chasing their first gold after making seven semi-finals, and India whose Olympic run-in was plagued by team controversy.

The eight-times champions haven't won a medal since 1980. They take on the Dutch in their opening pool game on Sunday evening, when the steamy summer heat should have eased.

The Australian women were the first team to win back-to-back golds in 2000 and are keen to extend their record-setting trend. But the Hockeyroos have been dogged by injury in the past weeks.

Argentina are the team to beat. Eleven of their 16 players were at Sydney 2000 when the team won silver and since then they have won the world championships and taken the number one rank.

The Dutch are also strong, led by player of the year Mijntje Donners and keen to end a double run of bronzes. Fourth-ranked China are shooting for their first Olympic medal after shocking the hockey fraternity by winning the 2002 Champions Trophy.

Hockey starts on Saturday and runs through August 27.