Andrea Pirlo missed a last minute penalty for ten-man Milan as two first-half goals from Sergio Floccari and Antonio Langella gave a gutsy Atalanta their first win at the San Siro since 1991.

Veteran Rossoneri captain Paolo Maldini pulled a goal back four minutes from time, but the visitors held out to complete an unlikely double over the European champions following a victory in the reverse fixture earlier in the season.

All eyes were on Brazilian teenager Alexandre Pato following his debut goal for Brazil in their midweek friendly against Sweden at the Emirates Stadium.

Perhaps the weight of expectation was too great for the 18-year-old striker as his runs down the left flank looked short on imagination and he was bundled off the ball with alarming ease by a resolute Atalanta back four.

The opening half hour was tame, with the Atalanta offside trap frequently catching Milan's forwards out. Although the Rossoneri looked the more confident of the two sides and retained possession well, they failed to carve out any real goalscoring opportunities.

The closest they came was on seven minutes when an unmarked Gennaro Gattuso struck on the volley from outside the penalty area. The boisterous Italian's effort flew over the bar and Milan were left wondering what might have been.

Atalanta's attempts at going forward were no more effective, and their only shot on target in the opening half hour was a feeble effort by Atalanta forward Floccari, who looked rather anonymous until he struck decisively minutes later.

Quite suddenly, the strength and confidence disappeared from Milan's play as Floccari bundled home after getting on the end of a superb, low ball into the area by Ferreira Pinto on the right wing.

Floccari's first strike was parried by goalkeeper Zeljko Kalac but the striker made no mistake on the second attempt from a few yards out.

Milan went into meltdown and Atalanta doubled their lead three minutes before half-time when the lively Langella struck powerfully past Kalac from inside the area.

The move began when Clarence Seedorf was easily dispossessed on the edge of the Atalanta box and Floccari led a quick counter-attack. He squared to Langella on the left wing who skipped past Massimo Oddo, controlled brilliantly inside the area and fired past Kalac.

Under-pressure Milan boss Carlo Ancelotti's half-time team talk did the trick and Milan came out blazing in the second half. Italian teenager Alberto Paloschi replaced Alberto Gilardino to accompany fellow youngster Pato up front as Milan chased a goal.

Two minutes into the first half Seedorf's strike from inside the six-yard box was disallowed for offside, but Milan continued to power forward.

Another disallowed goal on 76 minutes justifiably infuriated Ancelotti. Massimo Ambrosini was judged to have fouled Kalac as he headed into the back of the net in what looked like an overly harsh decision.

But there was nothing wrong with Maldini's close-range header ten minutes later, and the game's momentum shifted firmly back to Milan.

Moments after, Alessandro Nesta was sent off for a rash challenge on Ferreira Pinto, but this didn't prevent Milan from continuing their onslaught and they were awarded a penalty when Ambrosini was hacked to the ground in a sandwich between two Atalanta defenders.

After a long delay while the Atalanta players protested, Andrea Pirlo stepped up to take the spot-kick and Ferdinando Coppola, on loan from Milan, pulled off an excellent save to deny the home side a draw.

Ancelotti will lament another shambolic home performance from his team, who are now in real danger of missing out on the fourth Champions League spot in Serie A.

With Udinese's 3-1 victory over Fiorentina, Milan are now in sixth place on 49 points, one behind Udinese.

The reigning European champions are four points adrift of the fourth Champions League qualifying berth with seven games to play, but Ancelotti has said he is not in danger of being sacked even if they have to play in the UEFA Cup.

Udinese 3-1 Fiorentina

Fiorentina still occupy fourth spot but Udinese are now just three points behind in fifth after a confident home victory over their rivals.

Swiss midfielder Goekhan Inler put Udinese ahead with a fierce shot in the first half before substitute Christian Vieri equalised for the visitors with a header.

Italy striker Antonio Di Natale then ran half the length of the field to put the hosts back in front and Fabio Quagliarella nodded in their third.

Juventus P-P Parma

The match was postponed as a mark of respect for a Parma fan who was accidentally knocked down and killed by a Juventus supporters' coach at a service station on the way to the game.

Police said the two sets of fans had been exchanging insults and the coach driver had been attempting to leave quickly to avoid trouble.

Catania 1-2 Torino

David Di Michele rounded the keeper after Alessandro Rosina's cute pass to give the visitors victory and leave Catania in deep relegation trouble.

Home striker Gionatha Spinesi netted early with a powerful header from a corner but Torino hit back quickly with midfielder Aimo Diana slotting home after being left unmarked in the box.

Empoli 0-2 Sampdoria

The bottom side gave a limp display with UEFA Cup-chasing Sampdoria winning easily.

Paolo Sammarco scored on seven minutes before Lino Marzoratti contrived to put through his own net. The visitors could have score several more.

Genoa 2-0 Reggina

Genoa's Italy striker Marco Borriello netted his 18th of the league season to top the scoring charts and leave Reggina still two points of safety.

Borriello scored from a tight angle in an open game with Marco Rossi making sure of the win in stoppage time.

Livorno 0-0 Siena

Livorno are hovering over the drop zone after a poor game with few opportunities.

The point lifts perennial strugglers Siena up to 12th.

Eddie de Oliveira / Eurosport