Hayne, 28, quit the NFL after just one season to try to play rugby sevens for Fiji in this year's Rio Olympics.
The former San Francisco 49er previously played for Paramatta Eels in Australia's National Rugby League.
"I thought the boys needed a bit of added competition," said Fiji coach Ben Ryan.
"Jarryd has trained well. In attack he is comfortable on the ball, he has good spatial awareness and has good footwork. In defence he is a good tackler."
Fiji need eight points to claim this season's World Series title.
Hayne, who joined the Fiji camp as an injury replacement, left Australia's NRL in 2014 to pursue a career in the NFL as a running back.
He played international rugby league for both Australia, where he was born, and Fiji, who he qualifies for via his father.
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The Suffolk Chamber of Commerce said the work could help boost the county's economy by more than £350m a year.
In 2013, the government announced a £1.5bn upgrade of the Cambridgeshire section of the road, ruling out initial plans for a toll.
Suffolk Coastal MP Therese Coffey said the road was currently "not delivering" a "quick and efficient" route.
"Businesses rely on goods coming into the port of Felixstowe being transported in a quick and efficient manner, something the road is not currently delivering on," said the Conservative MP.
The twelve sites identified stretch from Exning to Felixstowe, and include the Copdock Interchange.
The areas named in a document called  No More A14 Delays also includes junctions in Exning, Bury St Edmunds, Ipswich and the Orwell Bridge.
It calls for various improvements, such as extra capacity at junctions, better links with other roads, improved parking facilities for lorry drivers, extra lanes and reduced speed limits on the Orwell Bridge.
The document states: "An end to congestion on the A14 in Suffolk could generate up to £362m of extra gross value added (GVA) per year, saving the A14 user an average 13 minutes per day in travel time, and creating an additional 7,000 jobs."
Jo Churchill, Conservative MP for Bury St Edmunds, said the route was crucial as "nearly 30% of all the UK's container trade passes through Needham Market, Stowmarket and Bury St Edmunds along the A14".
Nick Burfield, policy director at Suffolk Chamber, said: "The chamber and our partners are very concerned that, following the success of the 'No Toll Tax on Suffolk' campaign and the proposed Cambridge to Huntingdon improvements, the government may now regard the A14 as 'done'.
"This is far from the case."
A Department for Transport spokeswoman said: "The government is committed to regularly reviewing the needs of England's strategic road network.
"We will be outlining plans for developing the next Road Investment Strategy later in the year, and we want every community affected by heavy traffic to have their chance to get involved."
Former NFL and rugby league player Jarryd Hayne is in Fiji's squad for this weekend's final round of the World Rugby Sevens Series in London.
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Campaigners calling for improvements to the A14 have listed 12 sites they say are in need of improvement.