Neither The Blues or The Saints have had the pleasure of the Berkshire-based official refereeing any of their games so far this season.
In total Iain Williamson has taken charge of 14 games this season in which he has handed out 53 yellow cards and 3 reds.
G D Scott and M G West will be be Iain Williamson's assistants for the match at St Mary's on Wednesday evening.
For a detailed head-to-head between the two sides, click here