World number two Kim Clijsters turned in a stunning performance as Belgium booked their place in September's Fed Cup final against Italy.

The 23-year-old overwhelmed American opponent Vania King 6-0 6-1 in just 55 minutes to open up an unassailable 3-0 lead over an understrength USA team in Ostend.

The victory marks Belgium's first Fed Cup defeat of the US in five attempts.

In an entirely one-sided first set, the 17-year-old King won just nine points as Clijsters cruised to a 6-0 whitewash in just 23 minutes.

King then finally held her serve at the start of the second but Clijsters broke again in the third game and made short work of the rest of the set.

She clinched the match with yet another break to ensure Belgium's first Fed Cup final appearance since 2001, when Clijsters helped her country to a 2-1 defeat of Russia in Madrid.

The two dead rubbers were shared as the tie ended 4-1 to Belgium.

Earlier, Flavia Pennetta had booked Italy's place in their first-ever Fed Cup final with her straight-sets defeat over Spain's Lourdes Dominguez-Lino.

Pennetta's 6-2 6-4 win opened up an unassailable 3-1 advantage for Italy after four rubbers of the semi-final on the clay in Zaragoza.

Italy had raced into a 2-0 lead on Saturday thanks to Pennetta's defeat of Anabel Medina Garragues and Francesca Schiavone's win over Dominguez-Lino.

Garragues beat Schiavone in the third rubber to offer Spain some hope, but Pennetta, ranked 18 in the world, broke three times in the opening set to pile the misery on Dominguez-Lino.

The second set was a tense affair, with the 24-year-old Pennetta opening up a 4-2 lead only to be pegged back to 4-4 by Dominguez-Lino.

Pennetta immediately broke back, however, before serving out the match.

The dead doubles rubber was not played due to the extreme heat.