Barcelona have launched a complaint to UEFA over the state of the pitch at the San Siro following their goalless UEFA Champions League encounter.
The Catalans went into the game as firm favourites but failed to make that advantage count in the first leg of their quarter-final showdown.
And coach Pep Guardiola raised concerns about the condition of the pitch after the game.
He said: "We adapt to everything, we come and we play. But it's a problem for the quality of the occasion. It's difficult when the pitch is in this state."
The Primera Liga side later released a statement on their official website that said: "FC Barcelona has lodged a complaint with UEFA over the state of the Giuseppe Meazza (San Siro) stadium during the Champions League match."
Meanwhile, AC Milan striker Zlatan Ibrahimovic is confident his team can qualify for the semi-finals at the expense of Barca.
The Rossoneri held the reigning European champions to a goalless draw on Wednesday and head to Camp Nou next Tuesday for the return with a realistic chance of causing an upset.
"I am optimistic," Ibrahimovic told Gazzetta dello Sport. "We have already played in Barcelona and we know what to expect.
"Everyone knows Barcelona have more possession than any other side in the world so we did well and created quite a few scoring opportunities.
"The goalless draw is a good result and keeps our option open. Now we will see what happens in Barcelona."