AC Milan were held to a 0-0 draw at San Siro in a hard-fought contest by a Newcastle United side returning to the Champions League after a two-decade absence as the hosts spurned numerous opportunities in the Group F opener on Tuesday.
"We're disappointed, because when you play like this, you have to win," Milan manager Stefano Pioli said.
"The performance was all-round good, but we wanted to win. Our aim is to progress from this group and we wanted to start well. We didn't take easy chances."
Last year's Champions League semifinalists enjoyed a dominant opening spell and tested Newcastle goalkeeper Nick Pope with long-range efforts from Tommaso Pobega and Leão before Samuel Chukwueze had a header saved.
The best opportunity of the first half fell to Leão in the 34th minute but the 24-year-old miscued an elaborate backheel after skipping past two defenders in the penalty area.
Though Newcastle defended better after the break, Milan continued to press in their search for an opener.
Half-time substitute Alessandro Florenzi found Leão with an inch-perfect cross in the 74th minute, but the Portuguese again failed to find the target as he put his header over the bar.
At the other end of the pitch, the visitors' efforts were limited to counter-attacks.
"It was emotional. We take this draw and point, a point we fought to get and we're happy about," said Newcastle midfielder Sandro Tonali, who left Milan in the close season.
But the draw could hurt both teams in a tough group featuring French champions Paris Saint-Germain and 1997 European Cup winners Borussia Dortmund, who meet later on Tuesday.
Milan next travel to Germany for a clash with Dortmund, while Newcastle host Kylian Mbappé's PSG at St James' Park.
- José María Sánchez Martínez