The former Celtic star started for Samsunspor in their eventual 1-1 draw against Sivasspor. That's despite Swansea not officially confirming the 27-year-old's departure until Monday morning.
Ntcham's future with the Championship club had been unclear for the last few weeks.
Despite manager Michael Duff seemingly preparing to include him in his plans this season, reports in Turkey claimed a fee had been agreed for the midfielder the week before the start of the season, according to Wales Online.
The Welsh outlet say those suggestions were denied by Swansea insiders and even Ntcham's representatives.
But on the evening before their opening game against Birmingham, Ntcham called Duff, stating that he didn't want to be considered for selection.
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The press were then briefed that a fee for the midfielder had been agreed, and the Turkish club later announced their new signing a few days later.
But in a bizarre twist, those inside Swansea said the deal hadn't been completed yet, with Duff suggesting before his side's game against West Brom that it hadn't gone through.
"It's between the two clubs," he said. "As far as I'm concerned, I'm not expecting to see Olivier again.
"But he's definitely not signed for them yet. It's between the two clubs and they need to come to an agreement.
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"As far as I'm aware, he hasn't signed, but am I expecting to see him again? No."
Less than 24 hours later, Ntcham made his debut in Turkey, with Swansea still not providing any official confirmation of his departure.
The ex-Manchester City youth player joined Swansea from Celtic in 2021, making 82 appearances, scoring 12 goals and making six assists.
Swansea finally announced his exit from the club on Monday in a brief statement.
It read: "Swansea City can can confirm midfielder Olivier Ntcham has left the club.
"The Cameroon international departs following a two-year spell in SA1; all regulatory paperwork required to be submitted by Swansea City regarding the player's exit has now been completed.
"Ntcham scored 12 goals in 82 appearances in all competitions for the Swans."