The Lions conceded their first defeat in the Champions League this campaign after Moussa Marega’s 49th-minute header separated both sides.
Onyekuru was in action for the full duration and had a chance to fire the Turk Telekom Stadium outfit ahead in the 39th minute but could not find the back of the net with his shot.
Following the ‘unfortunate’ outcome, the 21-year-old thanked the fans that travelled to support the team and assured that the Turkish champions will bounce back in subsequent games.
“Thank you to the traveling supporters that made the journey tonight. It was a close game but unfortunate result. We will bounce back,” Onyekuru wrote Instagram.
Galatasaray dropped to the third place in the Group D standings behind Porto and Schalke 04 with three points from two games.
They will aim to pick up maximum points when they visit Antalyaspor in Saturday’s Turkish Super Lig fixture.