Cape Town - The Free State Cheetahs' Currie Cup aspirations have been dealt a massive blow after prop Coenie Oosthuizen was ruled out for the remainder of season.Oosthuizen injured his neck in his team's 25-all draw at home to the Golden Lions over the weekend and according to the Volksblad newspaper, will be out of action for about four months.Oosthuizen is expected to undergo surgery on Tuesday in Bloemfontein. Cheetahs team doctor, Ian Morris, told Volksblad that Oosthuizen injured a cushion in his vertebrae - similar to an earlier injury suffered by Springbok captain John Smit.The prop is only expected to return to action in next year's Super Rugby tournament.WP Nel - who has recovered from a calf muscle injury - will take Oosthuizen's place in their clash against the Pumas in Witbank on Friday.The Free Staters were further depleted with the news that young flyhalf sensation Johan Goosen will miss the trip to Witbank. Goosen left the field concussed against the Lions, but the Cheetahs are hopeful he could return for their last round-robin clash at home against Griquas.Sias Ebersohn will take Goosen's place at flyhalf.Cheetahs coach Naka Drotské described Oosthuizen's injury as unfortunate."Even though we're lucky that WP (Nel) can come back in Coenie's place, it's not nice to lose Coenie. He's playing unbelievably well. His work ethic is very high."The Cheetahs' clash against the Pumas at the Puma Stadium kicks off at 19h10 on Friday evening.