James Graham left the field with a concussion against the Roosters in Round 10.

Bulldogs skipper James Graham is set to miss a month of football after suffering a hamstring injury against the Dragons on Monday night.

Scans taken on Wednesday revealed the extent of the injury, which is expected to rule the star prop out until the Bulldogs' Round 19 clash with the Parramatta.

Sam Kasiano will start at prop in Graham's place alongside Aiden Tolman against the Titans this weekend.