KOTOR, Montenegro (AP) — When the Red Sharks lose, Montenegro mourns.

The water polo team of this tiny Adriatic Sea country, the pride of Montenegrin sports, lost 7-5 to Croatia, their wartime Balkan adversary, in the Olympic semifinals yesterday, triggering despair in the ancient walled city of Kotor.

“This is a disaster,” Mladen Martac said as he watched the game at the Vardar cafe in the city centre. “If it was football, basketball, or some other sports, it would hurt... but this is water polo, our beloved game.”

Montenegro reached the semifinals at the London Olympics along with Italy and two other former Yugoslav republics, Serbia and Croatia. Serbia were due to face Italy in the other Olympic semi-final later yesterday.

The quarter-finals demonstrated the region’s power in water polo. Montenegro, population 625,000, beat Spain, population 47.2 million. Croatia, 4.7 million, beat the US, 312 million. Serbia, 7.3 million, beat Australia, 22.6 million.

Many doubted that after the bloody 1990s breakup of Yugoslavia, which won three Olympic water polo titles, the states that emerged could carry on the glory of the old communist country.

But many were wrong. Serbia have won three world and European championships since 1991. Croatia have captured one world and one European title in that time. Montenegro won the 2008 European crown.

The phenomenon of water polo dominance is nowhere more striking than in Montenegro, a picturesque southern European country nestled between pristine rocky mountains and the turquoise of the Adriatic.

Out of 13 Montenegro players on the Olympic roster, 12 come from two small coastal towns, Kotor and the summer resort of Herceg Novi, on the border with Croatia, where water polo grounds are cordoned off in the waters that dot nearly all villages.

Yesterday, old wooden goalposts and plastic line markers swayed in the hot breeze and the waves.

War broke out in Croatia after it declared independence from Yugoslavia in 1991, and 10,000 people died in the conflict. Montenegrin troops took part in the fighting around the walled city of Dubrovnik.

Lingering rivalry among the former Yugoslav republics is perhaps best seen in water polo, which triggers national pride and emotion.

“This is another revenge for what they have done to us during the war,” said Mate Bacic, a Croatian fan in the nearby ancient Croatian city of Dubrovnik. “We are defeating them in peace.”