Seabelo Senatla has been overall top try scorer for the past two series, and the speedster will be key to the Blitzboks' hopes of taking the next step up after being runner-up for the last four seasons. South Africa won the bronze medal at Rio 2016. David Becker/Getty Images North America/Getty Images/file
New Zealand is rebuilding after the disappointment of missing out on an Olympic medal, but veteran former captain DJ Forbes (pictured) has made a record 80th tournament appearance for the 12-time series champion in the Dubai opener. Former players Scott Waldrom and Tomasi Cama will be interim coaches until June 2017, when Scotsman Clark Laidlaw takes over from the departed Gordon Tietjens. PASCAL GUYOT/AFP/AFP/Getty Images/file Henry Hutchison (above) was last season's rookie of the year, scoring 27 tries, and the 19-year-old will again be a key player for Australia. Sam Caslick, brother of Olympic women's gold medalist Charlotte Caslick, is one of the new faces in the squad but her boyfriend, captain Lewis Holland, is ruled out with long-term injury. Daniel Munoz/Getty Images AsiaPac/Getty Images/file Gaston Revol (right) will make his 50th tournament appearance at the Dubai season-opener -- only head coach Santiago Gomez Cora (61) and Nicolás Bruzzone (55) have played more for Pumas Sevens. The Argentina captain, 30, will hope to make amends for his crucial penalty miss in the sudden-death Olympic quarterfinal loss to Great Britain by winning the first sevens title of his career. PHILIPPE LOPEZ/AFP/AFP/Getty Images/file
After matching their best series finish, the Americans disappointingly failed to make the quarterfinals at Rio 2016. Speedster Perry Baker (above) will again be a key player after finishing second in the try stakes last season, with 48 in 55 matches. David Rogers/Getty Images South America/Getty Images/file
Tom Mitchell (above) captained Great Britain to a surprise silver medal at the Olympics, and he will be hoping England's Rio contingent can improve on last season -- which never matched the heights of reaching the final of the Dubai opener. Mark Kolbe/Getty Images AsiaPac/Getty Images/file
After a title-laden 20 years with New Zealand, legendary coach Gordon Tietjens has taken on a new challenge with Samoa. Englishman Damian McGrath guided the islanders to victory at the Paris Sevens but was sacked after only one season when the team failed to qualify for the Olympics. PATRICK HAMILTON/AFP/AFP/Getty Images Captain Terry Bouhraoua will be hoping for a more consistent season from France, which placed third at two tournaments but finished last at one -- and lost to Japan in the Olympic quarterfinals. Bouhraoua scored his 100th try in the 2016-17 season opener. PASCAL GUYOT/AFP/AFP/Getty Images/file
Team GB silver medalist Sam Cross (above) is one of Wales' co-captains, but leading try scorer Luke Morgan will miss the opening two rounds of the new season after a knee injury dashed his hopes of going to the Olympics. ISAAC LAWRENCE/AFP/AFP/Getty Images/file
After failing to qualify for the Olympics, Canada has turned to former Samoa coach McGrath. Points machine Nathan Hirayama (above) will again be a key player. Suhaimi Abdullah/Getty Images AsiaPac/Getty Images
German Davydov (right) enjoyed a strong debut series as Russia retained its core team status at the finale in London, with the 22-year-old's 20 tries in 53 games the team's second-best effort behind veteran Vladimir Ostroushko (26 in 40). Russia's men and women missed out on an Olympic place. Charlie Crowhurst/Getty Images Europe/Getty Images/file As it did at the 2015 Rugby World Cup, Japan proved to be the surprise package at Rio 2016, finishing fourth with a blend of homegrown talent and overseas imports. Former New Zealand assistant Damian Karauna has replaced head coach Tomohiro Segawa ahead of Tokyo 2020, and he went into the Dubai opener with only three players who had previous world series experience. David Rogers/Getty Images South America/Getty Images/file