The Hoops return to domestic duty following the 2-0 defeat to Feyenoord in their opening Champions League group fixture on Tuesday which saw them finish with nine men after both Gustaf Lagerbielke and Odin Thiago Holm were red carded.
Phillips missed the match in Rotterdam with an ankle injury picked up on his debut in the 3-0 win over Dundee last weekend but while the on-loan Liverpool defender is a doubt, he has not yet been ruled out of the trip to Almondvale.
"We'll see how Nat Phillips is," Celtic manager Brendan Rodgers told Sky Sports. "He obviously rolled his ankle quite badly last weekend so he'll miss the week [of training]. We'll see how he is. We've still got another 24 hours to go before we make the team.
"Apart from that everyone else [is] okay. Reo Hatate got more game time [against Feyenoord] and is still finding his way through to fitness, but it was good to get him on the field and play. But other than that there were no other injuries."
Celtic have a number of players on the treatment table including US international Cameron Carter-Vickers, summer signing Maik Nawrocki, defender Stephen Welsh and winger Liel Abada.
Asked for an update on Carter-Vickers, the lynch-pin of the Celtic defence, Rodgers added: "It's early October so he's still a wee bit away." Defensive partner Nawrocki is expected to be out until mid-October while Welsh and Abada face a longer spell on the sidelines with neither likely to return before Christmas.