This was their fourth Intercontinental Cup, the first since 1990, and made them the world’s most successful club side with 18 recognised international trophies.

The Rossoneri last took part in this tournament when it was still a one-off game known as the Intercontinental Cup, losing to Boca Juniors in 2003, but since the new format was introduced no European clubs had won it.

With Ronaldo injured, Inzaghi started upfront with support from Clarence Seedorf and Ballon d’Or Kaka. Alexandre Pato and Juan Roman Riquelme were ineligible for the two teams.

Both sides were aggressive from the start in Yokohama and after Kakha Kaladze closed down Rodrigo Palacio, Inzaghi’s angled drive skimmed the far post. The Italians kept the pressure on with Inzaghi and Seedorf, but Nelson Dida almost gifted Boca a goal on 11 minutes.

The ‘keeper completely missed the ball and was fortunate that Alvaro Gonzalez incredibly failed to get his finish on target.

Carlo Ancelotti switched tactics just 13 minutes in, pushing Kaka further up to partner SuperPippo with Seedorf in the Trequartista position. Kaka had a shot charged down by Gabriel Paletta, while Dida was at full stretch to capture Martin Palermo’s effort.

The deadlock was broken when the ball ricocheted around the box and Kaka threaded through for Inzaghi to take another of his classic poacher’s goals.

However, the lead lasted all of 120 seconds before some dismal defending allowed Palacio to equalise. A short corner was crossed in to find Palacio’s free header, as six Milan defenders remained static.

Gonzalez also found a ridiculous amount of space to nod just past the post soon after, while the impressive Gabriel Paletta continued to clamp down on Kaka. Inzaghi had timid penalty appeals waved away, Dida grabbed a deflected Ever Banega free kick and Neri Cardozo’s shot was charged down for a corner.

A Kaka screamer from the edge of the area was deflected and from the resulting corner there were more penalty appeals for pushing.

On the stroke of half-time Seedorf went on a surging run and his strike was too central to truly trouble Mauricio Caranta.

Milan were more determined after the restart and within five minutes restored their advantage with an unexpected hero. Andrea Pirlo’s free kick got a touch off Massimo Ambrosini and Alessandro Nesta came charging in with a powerful finish.

Pirlo had another penalty shout, then Kaka and Inzaghi combined in the box to test Caranta. But Boca were very unlucky not to equalise once again on 58 minutes, as Hugo Ibarra’s fantastic long-range effort cracked against the far post and the rebound was just beyond Palermo.

Milan took the hint and extended their lead in curious circumstances. Paolo Maldini was on the ground injured, but Gennaro Gattuso passed forward for Kaka to sprint to the byeline, confuse the defender and place the ball between Carente and the near post from the tightest of angles.

Gattuso took a knock and limped off for Emerson, while Boca introduced Pablo Ledesma and Leandro Gracian.

Palacio fired a half-volley over as Ambrosini came tearing in, but moments later Milan made it 4-1 with a classic counter attack. Seedorf ran forward from the centre circle, rolled across for Kaka who instead of shooting provided a perfect assist for Inzaghi to sweep home totally unmarked.

Kaka was about to grab a fifth as he surged between defenders and Paletta cynically shoulder-charged him off the ball in the D. Pirlo tried to curl the free kick under the wall as it jumped and it was just wide of the target.

The drama was not over yet, as 13 minutes from time Kakha Kaladze was shown a straight red card for a mistimed tackle that went studs-up on Palermo’s ankle. Morel curled the resulting free kick over and Dida blocked a Palermo header and Palacio stinger as Boca saw their hopes suddenly revived.

Although playing with 10 men, Kaka threatened a fifth goal by nodding Marcos Cafu’s cross over the bar from seven yards.

Once again Milan struggled to defend from a set-piece, particularly with Kaladze off the field, as a corner kick was not dealt with effectively. Dida did well to parry a powerful Sebastian Battaglia effort from the edge of the box, but could do nothing on Paletta’s follow-up deflected off Ambrosini.

The referee evened out the red cards with a straight dismissal for substitute Ledesma, who had only been on the field for 20 minutes, for a very high challenge on Kaka.

In stoppages Cristian Brocchi – who had just replaced Seedorf – threaded through for Kaka and Caranta blocked the shot with his legs.

In the other match, Japanese side Urawa Red Diamonds ensured third place by squeezing past Tunisians Etoile du Sahel on penalties after it had ended 2-2.

Boca 2-4 Milan
Scorers: Inzaghi 21, 71 (M), Palacio 23 (B), Nesta 50 (M), Kaka 62 (M), Ambrosini og 85 (B)
Boca Juniors: Caranta; Ibarra, Maidana, Paletta, Morel Rodriguez; Gonzalez (Ledesma 67), Battaglia, Banega, Cardozo (Gracian 68); Palermo, Palacio
Milan: Dida; Bonera, Nesta, Kaladze, Maldini; Gattuso (Emerson 65), Pirlo, Ambrosini; Kakà, Seedorf (Brocchi 86); Inzaghi (Cafu 76)
Ref: Rodriguez Moreno (Mex)
Sent off: Kaladze 77 (M), Ledesma 86 (B)