Leicester Tigers director of rugby Richard Cockerill believes his side can afford just one more loss at the most if they are to have any chance of progressing from their European Champions Cup pool.
The Tigers campaign suffered a setback when they were beaten 15-3 by Scarlets in Llanelli, leaving Toulon clear at the top of the group after posting two wins.
There were no excuses from the Tigers camp after their defeat at Parc Y Scarlets.
"We conceded two pretty soft tries," Cockerill said. "Our execution was very poor. We couldn't hold on to the ball and if you do that and give points away you are going to lose.
"Take nothing away from Scarlets, they played well and worked exceptionally hard. But we cannot be that inaccurate and expect to get anything from the game.
"We have to win at least four games to get out of the group. It is all to play for but getting nothing out of this game makes it exceptionally difficult."
Skipper Ben Youngs added: "The group is tough enough. You can probably afford to lose one away game and then you need to get a bonus point.
"Toulon back-to-back is a big challenge which has become somewhat bigger."