Wasps scrum-half Joe Simpson could be sidelined for a month after suffering knee trouble.
But Simpson, who was hurt during Wasps' Aviva Premiership victory over London Welsh three days ago, is unlikely to require surgery.
"Thankfully it doesn't look like it needs an operation," Wasps rugby director David Young said.
"At the moment he is looking at around three-four weeks of rehab, which is much better than we first thought."
Simpson, 24, was capped by England during the World Cup in New Zealand last year.