Zlatan Ibrahimovic came on as a second-half substitute in his first game since returning to AC Milan as his side were held to a goalless draw by Sampdoria.
The 38-year-old Swedish striker, who helped Milan win Serie A in 2010-11 and has signed a six-month deal, replaced Krzysztof Piatek after 55 minutes.
Ibrahimovic had two headed chances but one was cleared off the line and the other was saved by Emil Audero.
The result leaves Milan 12th, four places ahead of Sampdoria in 16th.
Sampdoria had chances to win the game but former Southampton striker Manolo Gabbiadini shot wide from the edge of the penalty area after he had taken the ball around goalkeeper Gianluigi Donnarumma.