With 16 players absent on international duty with Wales, Ireland and various under-20 squads, the former Bridgend Ravens head coach had little choice with his team selection but welcomed back captain Alun Wyn Jones from a toe injury for his first RaboDirect PRO12 since November.
Aironi, who were playing their first RaboDirect PRO12 fixture since a 20-6 reversal of Connacht on January 7th, were forced into a late change on the bench and brought in prop Luca Redolfini for the injured back row Filippo Ferrarini and their lack of action told early on.
Ospreys were first off the mark with a fifth-minute penalty try following a collapsed scrum, converted by Biggar, and they continued to dominate territory and possession with Richard Hibbard looking particularly bright.
Despite forcing their Italian opponents back, Ospreys were struggling to find a way past a resolute Aironi defence before Biggar added a further three points to extend his side's lead on 25 minutes.
Aironi's Italian flanker Mauro Bergamasco added to his side's woes on the half hour when he was yellow carded for an elbow to the face of Rhys Webb but the Welsh region were unable to capitalise and went in at the break with a ten-point advantage.
Four minutes after the restart Biggar secured another three points when he slotted over another penalty to establish yet more control for the hosts before Aironi's Naas Oliver showed a lack of composure in front of the posts - the fly-half missing two penalties in two minutes.
Biggar showed him how to do it on the hour mark by adding another penalty to his ever-growing total.
In danger of being whitewashed, Aironi winger Sinoti Sinoti added some consolation for Phillips' side by rushing under the posts eight minutes from time and while Oliver added the extras, Ospreys centre Andrew Bishop sealed Tandy's first victory with a try four minutes from time - converted by substitute Matthew Morgan.
|Ospreys Score Card|
|Aironi Rugby Score Card|