SAN FRANCISCO • Australian rugby league convert Jarryd Hayne endured a difficult debut for the San Francisco 49ers before the National Football League giants overpowered the Minnesota Vikings 20-3 on Monday.

The 27-year-old, who only switched sports earlier this year, was a surprise inclusion in San Francisco coach Jim Tomsula's starting line-up at the Levi's Stadium for the long-awaited season-opener.

He walked away from a glittering career in the top-flight National Rugby League a year ago in a bid to realise his dream of playing in the NFL and earned a spot on the 49ers' 53-man squad this month.

But his dream debut turned into a nightmare with his very first touch in the second quarter. He fumbled what should have been a straightforward punt return near the 43-yard line to concede a turnover.

He was only a fleeting presence thereafter, upstaged by fellow running back Carlos Hyde, who rushed for two touchdowns to finish with 168 yards from 26 carries.

Hayne finished with 13 yards from four carries. Nevertheless, he put a positive spin on his display, telling reporters: "It started a bit shaky but it was good to get out there and get a couple of runs."

He said his fumble came about after he was distracted by the oncoming Minnesota rushers. "I was in emergency mode, trying to make a play, make a catch, and it didn't happen."

AGENCE FRANCE-PRESSE, REUTERS