Tigers hit by injury to Wallaby star Toomua
The 26-year-old – capped 33 times including last year's World Cup final defeat by the All Blacks – is to undergo knee surgery.
He suffered the injury in last Sunday's crucial 27-17 European Champions Cup win over last season's finalists Racing 92.
"Richard Cockerill [the club's Director of Rugby] confirms Matt Toomua having surgery on his knee and will be out for around six month," Leicester said on Twitters.
"We wish him a speedy recovery."
Toomua, who joins England centre Manu Tuilagi on the sidelines, signed for the Tigers from the Brumbies on a three-year contract earlier this season.
This will bring down the curtain on his Test career.
He has not accrued the minimum 60 caps to be eligible for selection.
He made just two appearances for the Tigers – and was fortunate to escape a red card for a tip tackle on his debut for the club in the 42-13 Champions Cup thrashing by Glasgow.
Agence France-Presse
