World number 132 Alexa Glatch has been chosen by the USA to open the Fed Cup final against Italy's Flavia Pennetta on Saturday.

Serena Williams had originally been expected to play in the singles for the US team, alongside teenage star Melanie Oudin, a star of the recent US Open.

However, the new world number one withdrew last week, leaving Glatch - who won two rubbers in USA's semi-final victory over the Czech Republic in April - to keep her place.

Saturday's second singles rubber sees Francesca Schiavone take on Oudin.

The Italians, winners in 2006 for the only time in their history, will start favourites to claim the trophy given they are playing on their favourite clay surface in Reggio Calabria.

However, to do so they will have to beat the US for the first time in 10 meetings in the competition. The USA are seeking an 18th Fed Cup title.

Sunday will see the two reverse singles, followed by the potential decisive doubles rubber.

Italy have named Sara Errani and Roberta Vinci for that clash, with the US choosing doubles specialist Liezel Huber alongside Vania King.