Ospreys coach Toby Booth has been faced with the challenging task of piecing together a team amid what he has described as a "horrific" unavailability list.He is without no fewer than 18 players for the URC trip to Belfast to face Ulster this evening (7.35pm) through injuries and Wales internationals being rested.It's resulted in him selecting a pretty unfamiliar looking match-day 23.Hooker Lewis Lloyd is pressed into service as an emergency blindside flanker, with the back five of the scrum being the hardest hit area, as demonstrated by Will Greatbanks and Lewis Jones both making their first starts at lock.South African backs Evardi Boshoff and Dan Kasende take their season bows, with fly-half Owen Williams slotting into the injury-hit centre as he returns to action.Then, on the bench, you’ve got two forwards stepping up from the second-tier Super Rygbi Cymru competition, with teenage Swansea lock Dan Gemine and Aberavon back row Rhys Thomas in line to make their regional debuts.Booth said: "We've got a lot of people out in similar positions, which makes it challenging."We'll do our best to find a way, like we always do, and we won't be lacking in effort, that's for sure."I'm guessing here, we have roughly around 55%-60% players [fit] which is horrific."It is not just in number, but in quality."As for Ulster, they are boosted by the return from injury of Ireland centre Stuart McCloskey (above) as they look to build on last weekend’s victory over Connacht.They will be favourites to earn a third home win in a row and assistant coach Dan Soper said: "When we get to the end of this block we will reflect on the first six games."We will look back at what has went well and what areas do we need to drill down on in that