Gilroy has eight in his last seven outings while Webb, despite missing a chunk of the season on international duty, has amassed his total despite just 12 starts.
Gilroy's hopes of re-taking the lead hinge on a trip to Scotstoun this weekend there they will face table toppers Glasgow Warriors.
The semi-final is an immediate repeat of last weekend's fixture, which resulted in a convincing 32-10 victory for the hosts, Finn Russell leading the way with a try double and 12 points from the tee.
Glasgow are also embarking on their fourth straight play-off campaign - last year witnessed their first Final appearance - and boast the competition's only 100 per cent home record this season.
Webb, meanwhile, faces a trip to Thomond Park where Munster will host the Ospreys on Saturday.
That clash also features the two nearest challengers for the honour of top try-scorer in Munster duo CJ Stander and Simon Zebo on nine and eight respectively.
Limerick will also play host to a nail-biting battle between two fly-halves, fighting it out to be the GUINNESS PRO12 top point-scorer for the season.
Ian Keatley leads the way with 170 while Dan Biggar, named alongside Ospreys teammate Webb in the GUINNESS PRO12 Dream Team of the Season, is just two behind on 168.
Ian Madigan is back in third with 140 points to his name but the Rhino Golden Boot winner - by virtue of his superior accuracy over 22 rounds - will not have the chance to close the gap after Leinster finished fifth.
Dan Evans, meanwhile, will make his 100th GUINNESS PRO12 appearance should he feature for the Ospreys this weekend, while Ulster fly-half Ian Humphreys is just two points away from reaching 500 in the competition.
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Guinness PRO12 Ulster News
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