The club's longest serving player, now in his ninth season at Turf Moor, came into the side at Derby for his first game of the season, but two games later, at Peterborough, suffered a groin injury that wasn't expected to keep him out more than a couple of weeks.
Unfortunately it has taken longer and by the time he comes back it will have been four months, by some considerable distance the longest injury he's had in his time with the Clarets.
Eddie Howe explained today: "Brian had an injection in his groin which will put him back four to six weeks but hopefully that will get to the heart of the problem and he will be back with us.
"It's been a nasty one for him. He had got to the stage where he could do everything bar the long kicking. He just felt little twinges in his groin and we felt we had to get it seen to so he's been to see the specialist and hopefully that's sorted it."
Jensen has played a total of 305 league and cup games for Burnley since Stan Ternent signed him from West Brom in the summer of 2003. For much of his time he's been first choice goalkeeper and had just won back his place again when this injury occurred.
Out of contract in the summer, he'll now be hoping to stake an early claim for a return to the first team to help earn himself a new deal with a further year taking him to the point where he would qualify for a testimonial.