Manuel Pellegrini moved quickly to defuse the Lucas Perez warm up issue which left the striker on the bench seething.
Sky Sports reported that the summer signing was due to come on for Arnautovic when the Austrian was injured but was eventually overlooked for Michail Antonio.
He was then seen in deep deep in conversation with goalkeeping coach Xavi Valero and appeared irritated by the decision to leave him as an unused substitute.
However, Pellegrini explained quickly after the game: “When Marko was injured, I called Lucas because he was doing a warm-up, and when I saw he was sat on the bench and Antonio was working and ready, that’s why I brought him on instead, rather than waiting for Lucas to warm up again.
“Antonio was ready, and Lucas had to warm up a little bit more.”