Pierce was in good form

The number two seed had little trouble seeing off the unseeded Spaniard 6-2 6-4 to set up a quarter-final date with compatriot Emilie Loit.

Loit was a 6-0 6-3 winner over Stephanie Foretz.

Russian seventh seed and defending champion Dinara Safina beat local hope Virginie Razzano 6-4 6-3.

Fifth-seed Elena Dementieva took less than an hour to beat Swedish qualifier Sofia Arvidsson 6-2 6-2 and cruise into the second round.

She will next face France's Nathalie Dechy, who humbled compatriot Marion Bartoli 6-0 6-2 for her first victory this year.

Meanwhile, Pierce has confirmed she will play in the Diamond Games tournament in Antwerp starting on Monday, 13 February.

The world number six, runner-up at both the French and US Opens in 2005, joins Australian Open champion Amelie Mauresmo and world number one Kim Clijsters in the field.

Clijsters' participation, however, depends on her recovery from the ankle injury that forced her to retire during her semi-final against Mauresmo in last month's Australian Open.