MILAN - Third-placed AC Milan continued to lose ground in the Serie A title race as they were held to a 1-1 draw by Atalanta after Teun Koopmeiners' penalty cancelled out Rafael Leao's superb early opener for the hosts on Sunday.

Milan, who last weekend missed the chance to go second when they lost 4-2 at mid-table Monza, are 13 points behinds leaders Inter Milan, who won 4-0 at Lecce earlier on Sunday and still have a game in hand.

Stefano Pioli's Milan side remain third on 53 points from 26 games, four points off second-placed Juventus.

"Tonight we lost two points. If there was a team that deserved to win it was us," Pioli told DAZN.

"We played our best match against Atalanta, we played with personality and quality without letting them shoot. The best performance of the week."

Atalanta, with one more game to play than the teams immediately above them, are fifth with 46 points, two behind Bologna in fourth.

Milan got off to a flying start when Leao broke the deadlock in the third minute, capping a solo run with a stunning shot into the top corner from a tight angle.

The Portugal forward ended his goal drought in Serie A, scoring in the competition for the first time in five months.

But Atalanta levelled against the run of play from the spot shortly before the break as Koopmeiners sent Mike Maignan the wrong way after a penalty awarded for Olivier Giroud's foul.

Milan continued to dominate the game after the interval with 70% possession against Atalanta, who travelled to San Siro off the back of five straight wins and remain unbeaten this year.

But Gian Piero Gasperini's side, who beat Milan 2-1 away in the Coppa Italia quarter-finals last month, were far from their top form. This, however, did not make Milan's task much easier as the majority of the home side's 20 attempts were off target.

Leao produced a superb lofted pass to find Christian Pulisic who controlled the ball well but sent his low shot just wide of the far post in the 69th minute before Ruben Loftus-Cheek was denied by goalkeeper Marco Carnesecchi.

"Milan are a great team, with very high values ​​and they put us in difficulty," Gasperini told a press conference.

"In the other matches against them we didn't have this type of difficulty, while tonight we suffered from their strength."

Atalanta are back at San Siro on Wednesday to face Inter. REUTERS