KAI Horstmann is facing four more weeks on the sidelines after the Warriors medical team decided he needs surgery on his rib injury.

The influential number eight has carried the problem since the end of last season but still played the first three Guinness Premiership games of this campaign before aggravating the injury after 55 minutes of the Wasps clash.

The 28-year-old former England Saxon is set to have a titanium plate fixed to the bone to aid the healing process in a bid to prevent future setbacks.

Despite the blow, Worcester director of rugby Mike Ruddock insists Horstmann’s deputy Netani Talei will not be wrapped in cotton wool.

Fiji international Talei is to start Thursday’s Amlin Challenge Cup clash with French outfit Montpellier at Sixways (7.45pm).

The Warriors boss said: “We’ve decided Kai will have a small operation in and around his rib to give a bit of fixation to it.

“He’s got a cracked rib and we believe we can help that along with a bit of surgery, so that’s going to happen and it will put him out for another four weeks.

“Basically, it is a small titanium plate around the rib to make sure it holds in place and doesn’t re-fracture. It is significant, but is not a major op like re-setting a shoulder or knee.

“We’ve got some really good options in the back row with Matt Cox, who is a number eight but can also play six and seven.

“He has played for England Under 20s previously, while locks Will Bowley and Graham Kitchener have also both played at six before.

“James Collins played at eight in the ‘A’ game on Monday and Jake Abbott is back as well after a toe injury, so we have quite a few excellent choices available to us with those kids.

“Having said that, Netani will figure on Thursday against Montpellier but there is a good chance he will then not play against Madrid the following Saturday so he can have a rest.

“Guys like Cox, Collins and Abbott will probably make up the back row against Madrid.”

No match has yet been targeted for Horstmann’s return to action as Ruddock will wait and see the outcome of the operation.

He added: “Kai should be back playing in four weeks, but he hasn’t had the surgery yet so we need to see how that is going to go.

“We don’t envisage any complications so hopefully we can then be really accurate about the timescale for his return.”