Jelavic missed yesterday’s match with a groin problem, and the Scottish champions suffered a further setback when Lafferty was carried off early on with a hamstring injury.
The Northern Ireland striker could be sidelined for up to five weeks.
Goals from David Healy – making his first SPL start of the season – and Sone Aluko in addition to an own-goal from Stephen Craigan sealed the victory but Rangers manager Ally McCoist said his dwindling numbers are a concern, with Kirk Broadfoot also sidelined yesterday.
He said: “Nikica didn’t make it with a groin strain, he attempted to train but he wasn’t fit enough to play or be involved. The injury to Lafferty is a big, big blow for us. I don’t know the full extent of the injury but it looks like he has pulled his hamstring and my guess would be four or five weeks. Hopefully Nikica’s is more short term.”
Jelavic has been the subject of intense speculation over his future and has been tipped for a switch to the Barclays Premier League.
Former Rangers striker Nacho Novo, who now plays for Sporting Gijon in his native Spain, has been training with his old club over the festive period while back in Scotland. Asked if he could be an option, McCoist said: “I can’t say we are interested and I can’t rule out interest in any other player either.”
Rangers remain two points behind Celtic, after the Parkhead side also enjoyed a 3-0 win yesterday, away to Dunfermline. Elsewhere, Aberdeen snatched a 2-1 win at Tannadice, and Kilmarnock won by the same scoreline at home to St Mirren.