A five-star AC Milan outside brushed aside Siena with ease in Tuscany to consolidate third place in the Serie A standings.
Andrea Pirlo opened the scoring from the penalty spot but it then became the Filippo Inzaghi show with the veteran striker scoring in each half to reach the impressive landmark of 300 career goals.
Alexandre Pato also scored two while Massimo Maccarone was on target for the beleaguered hosts, who were guilty of wasting a number of chances.
Paul Codrea also hit the crossbar for the Robur late on.
It took the Rossoneri just seven minutes to take the lead as Pirlo scored his first goal of the season from the penalty spot after Houssine Kharja brought down Mathieu Flamini on the edge of the area.
In the 11th minute the Rossoneri were dealt a blow as goalkeeper Christian Abbiati had to come off following a collision with defender Giuseppe Favalli. Dida came on as his replacement.
The lively Maccarone then troubled the Milan defence as he rounded two players before crossing a ball towards Kharja lurking at the far post.
Favalli did well as he just managed to put the ball out for a corner before Kharja could connect.
Maccarone also volleyed an effort wide from 22 yards as Siena looked to test Dida in the 25th minute.
Two minutes later Siena came even closer to finding an equalizer as Calaio headed a lovely Cristiano Del Grosso cross from the left wide of the target from a good position.
Siena midfielder Ahmed Barusso then tried his luck from long range but his right footed effort sailed over the bar in the 35th minute.
Moments later, Del Grosso fired a free-kick from the right wing into Dida's arms after Massimo Ambrosini brought down Kharja.
Robur captain Simone Vergassola also volleyed a lovely cross from Maccarone over the bar under pressure from Ambrosini.
But the Rossoneri doubled their lead in first half stoppage time as Inzaghi beat Siena goalkeeper Gianluca Curci for his 299th goal.
The striker connected well with a David Beckham corner to tap in left footed from the center of the area.
After the break Calaio saw a goal correctly ruled out for offside in the 52nd minute as he stroked home following a great run from Kharja.
Pato made it three for the Diavolo 10 minutes into the second half with a superb strike from range which left Curci well beaten.
Kaka, who had come on for Ambrosini at half-time, somehow missed the chance to make it four as he blasted over the bar unmarked from just inside the area.
Maccarone then pulled a goal back for the hosts two minutes after the hour mark with a well taken low shot into the right corner from the just outside the area.
However, any hopes of a Bianconeri fight back were dashed as Pirlo played a lovely ball through to Inzaghi who fired home his 300th career goal in the 71st minute.
Pato made it five for the guests as he latched onto a great long pass from Ronaldinho before rounding Curci to slot into an open net.
Siena had a chance to double their tally in the 82nd minute but substitute Nicola Amoruso put a Kharja low cross wide.
Codrea was then denied by the crossbar as he fired from the edge of the area following a Robur corner.
Beckham, unmarked in the area, put a shot just over the bar with the last action of the game.
