GLOUCESTER'S Wales number eight Gareth Delve will have surgery on July 9 to assess the damage to his Anterior Cruciate Ligament (ACL).
Delve will undergo his operation following consultation with specialist Andy Williams and will be out of action for a number of months and will miss the start of the season.
The 25-year-old suffered damage to his left knee during Wales' summer tour to South Africa and Gloucester's head coach Dean Ryan said: "Gareth is a tremendous individual and an outstanding player - someone we wanted to build around for the future.
"This injury is obviously a significant set-back to him and the club but I have no doubts he will be back in Gloucester colours next season. He has drive, determination and a willingness to succeed and I am sure that will come through in his recovery."
Delve made 20 appearances in all competitions for Gloucester last season following his summer move from Bath.
Meanwhile, flanker Akapusi Qera will see a specialist in London on Monday to determine the extent of his knee injury.
Fly-half Billy Burns was named Man of the Match after the 35-14 European Rugby Challenge Cup victory over Stade Rochelais on Thursday evening, and was full of praise for all his team mates for the win after a short turnaround.
Gloucester have been in good form in recent weeks, but Backs Coach Tim Taylor knows that the Cherry and Whites will have to be at their best on Thursday evening (kick off 7:45pm) against a Stade Rochelais side flying high this season.
Speaking to GRTV after the bonus point win over Bristol, back row Lewis Ludlow revealed that despite a tricky first half, Gloucester backed their skills to come through, a faith that was evident in a strong second half showing.
Willi Heinz scored Gloucester's second try as the Cherry and Whites overturned a disappointing first 40 minutes and 0-6 half time deficit, to earn a 26-18 Aviva Premiership victory over Bristol Rugby on Saturday.
Gloucester's much changed side had to overcome conceding an early try on Thursday evening, but responded in style to down Stade Rochelais by 35 points to 14 in the European Rugby Challenge Cup and set up a mouthwatering return fixture next weekend.
After taking 11 points from their last three games in the Aviva Premiership, including bonus point wins against Wasps and Bristol, Gloucester will be looking to continue their good form when they welcome La Rochelle to Kingsholm.