AC Milan were held to a goalless home draw by Bologna, leaving them one point clear at the top of Serie A.
Wins by defending champions Inter Milan and second-placed Napoli at the weekend put pressure on Milan to respond.
But the hosts struggled, with French forward Olivier Giroud’s header, well saved by Lukasz Skorupski, their best first-half effort.
Zlatan Ibrahimovic came off the bench after the break, but Bologna withstood late pressure to seal a point.
Bologna, in 12th place, were without coach Sinisa Mihajlovic on the touchline as he undergoes hospital treatment for leukaemia.
AC Milan have seven games left as they pursue their first Scudetto since 2011.