The defender did not take part with the official reason given that an injury issue has arisen in recent days.
Souttar has had injury problems in recent years at Hearts and is not being used in the fourth-round tie in east Ayrshire.
Talks are progressing between Rangers and Hearts officials and the Glasgow club are expected to push for a quick deal for Souttar before the January window closes.
Hearts are determined not to sell him on the cheap, although it remains to be seen if he will play in maroon again as the situation around his future intensifies.
Nathaniel Atkinson made his debut against Auchinleck after arriving from the Australian club Melbourne City. He performed at right wing-back.
Liam Boyce was also in the visitors’ starting line-up after recovering from a calf problem. The Northern Irishman is Hearts’ top goalscorer this season and led the forward line.
Auchinleck were seeking to cause a major cup upset against Premiership opponents. The West of Scotland Premier Division side play in the sixth tier of Scottish football but knocked out Championship club Hamilton in the previous round.
The draw for the fifith round takes place later on Saturday evening after Alloa Athletic play Celtic.