"It's going to be difficult for the officials in a very intimidating environment," said Sampson ahead of a game that could give England's women their first ever semi-final spot.
The Welshman said Olympic bronze medallist Canada had benefited from too many questionable decisions throughout their home tournament.
"It's a tough job being an official and when there's that pressure of home nation expectancy. It's very difficult to remain calm and make the right call," he said.
"Fact is that in the group stage Canada were awarded more fouls than their opponents in every game."
Canada won its opening game against China thanks to a last-gasp penalty from captain Christine Sinclair, and is unbeaten in the tournament, while England lost its opening game to France.
Ranked eighth in the world, two places below England, the host is attempting to reach its second World Cup semi-final.
"We're just looking forward to getting out there and giving England hell," said Canada's English coach John Herdman.
Former New Zealand coach Herdman said the pressure was off his side as it had been expected to win its first four games.
"This tournament and the success of it is resting on the shoulders of this team, you get knocked out in the group stage it was a failure, you get knocked out in the knockout round and the TV ratings have dropped and the tournament may disappear, now it's about looking forward.
"We're not looking at falling down or dropping out ... we're two games away from the final, a couple of opponents in our way.
"Let's do it. It's not just 55,000 but a whole nation waiting for one result."