UPDATE1-Soccer-Besiktas add Turkish league title to Cup win

* Besiktas secure 11th league title

* Completes double with Turkish Cup win

ISTANBUL, May 30 (Reuters) - Besiktas clinched the Turkish league title for the 11th time on Saturday with a 2-1 win away to Denizlispor, adding to their Turkish Cup success.

Besiktas fans streamed onto the streets of Istanbul to celebrate their first championship since 2003 while players embraced on the pitch in the western Turkish city of Denizli.

Slovak Filip Holosko opened the scoring for the Istanbul side in the 28th minute while Ibrahim Toraman extended the Black Eagles' lead in the 63rd minute with a superb long-range shot.

Brazilian Douglas Daniel Braga pulled one back for the home side in the 85th minute, but couldn't knock a superior Besiktas off their stride.

Surprise title contenders Sivasspor, who topped the league table for much of the last five months, finished second after a 2-1 defeat to Galatasaray, but qualify for the Champions League. Trabzonspor took the third spot after losing 2-1 to Fenerbahce.

It has been a bitterly disappointing season for Besiktas' major Istanbul rivals Fenerbahce and Galatasaray, who have both won the title 17 times and who finished in fourth and fifth place.