Wests Tigers' fast start to the NRL season has been slowed down by news Curtis Sironen will miss up to a month with a hamstring injury.
However the loss of their first-choice second-rower has been offset by the expected early return of former captain Robbie Farah, who could come back from his knee problem as soon as next week.
Sironen lasted just 10 minutes in last week's win over Manly before succumbing to a hamstring complaint that stemmed from a back issue.
"He strained his hamstring, related more to above it in the lower back. He's got some issues there. At this stage we're saying three to four weeks," Tigers physiotherapist Peter Moussa told the club website.
Tigers coach Jason Taylor named Kyle Lovett to start in Sironen's place for this week's match against Gold Coast, where they are gunning for their third straight win in the competition.
The prognosis is a lot better for 32-year-old Farah, who has yet to appear this season after tearing his meniscus in a trial against Cronulla in February.
The club has targeted Monday week's clash against Parramatta for Farah's comeback in what would be his first NRL game since standing down from the captaincy during the off-season.
"Robbie's going really well. He's done some running outside today. We're going to run a couple more times this week. The goal's Monday night against Parramatta," Moussa said.
Summer recruits Justin Hunt and Matt Ballin have also begun running, with Hunt aiming to return in round five and Ballin on track for a comeback in round 10.