(CNN) -- Inter Milan have won the Italian Serie A title for a fifth successive season -- and the 18th time in their illustrious history -- after Diego Milito's goal gave them a 1-0 win at Siena on Sunday.
Jose Mourinho's side needed nothing less than a victory to secure the Scudetto and they achieved that feat in the 57th-minute when striker Milito collected a pass from fellow-Argentine Javier Zanetti, before firing home a shot with the outside of his right foot.
A draw would have allowed second-placed Roma to snatch the title with a win at Chievo and Claudio Ranieri's side kept up their side of the deal with a 2-0 success.
Mirko Vucinic volleyed home Daniele De Rossi's through-ball in the 39th minute and Italian international De Rossi added a second on the stroke of half-time with a superb long-range strike.
With only 45 minutes remaining of the season, Roma were in pole position to win their first title since 2001 -- but Milito's strike ensured Inter became the first team since Juventus in the 1930's to win five titles on the bounce.
The result, which condemned Siena to relegation to Serie B alongside Atalanta and Livorno, also means Inter Milan will now face Bayern Munich in next weekend's Champions League final in Madrid with both sides bidding for a unique treble.
"This is an incredible joy, a reward for all the hard work we've put in over the year," Milito told reporters. "From tomorrow we will think about that great Champions Lague final."
Like the Bavarian giants, Inter have now added the league title to their domestic cup triumph -- and Saturday's Bernabeu showdown now ensures one of the two teams will secure a rare treble of trophies this season.
For Mourinho, who has overseen Inter's last two Scudetto wins, there is the added incentive of joining a select band of coaches to have won the Champions League with two different clubs, following his success with Porto in 2004.