Ana Ivanovic kept alive her hopes of a first title in 2009 by marching into the fourth round of the BNP Paribas Open.

The Serbian has endured a dramatic fall from grace since winning the French Open last June and taking over as world number one, and has lifted only one trophy in that time.

She has struggled in the first three months of this year but there were encouraging signs for the fifth seed in a 6-3 6-3 win over Gisela Dulko.

Ivanovic next faces 12th seed Flavia Pennetta, who survived a tough encounter with American qualifier Angela Haynes, eventually prevailing 4-6 6-4 6-1.

Seventh seed Agnieszka Radwanska eased into round four with a 6-1 6-4 victory over 25th seed Aleksandra Wozniak and will now take on Agnes Szavay, the 22nd seed who beat Kristina Barrois 6-3 6-4 today.

Nuria Llagostera Vives caused an upset by dumping out 21st seed Alisa Kleybanova 7-6 (7/2) 6-3 while Russian teenager Anastasia Pavlyuchenkova defeated Karin Knapp 6-2 6-4.

Fourth seed Andy Murray continued his comeback from illness by easing into the fourth round of the men's event at the expense of Paul-Henri Mathieu.

The 21-year-old saw off the Frenchman 6-3 6-2 in Indian Wells in only his second singles match since withdrawing from the Dubai Open quarter-finals last month with a virus.

Murray was happy with his form and improving fitness, saying: "It was very good apart from a couple of games.

"But I'm hitting the ball well and it was much better than the first match (against Albert Montanes).

"I felt good today. Physically I need to get a better. I was breathing harder than I'd like after some of the long points. But I was happy with my movement."

Tenth seed Fernando Verdasco, playing in his first tournament since beating Murray on his way to the Australian Open semi-finals, blitzed Richard Gasquet 6-3 6-2.

The explosive Spaniard had too much power for his French opponent and rattled off five games in row to seal victory and a fourth-round meeting with Philipp Kohlschreiber.

The German today won a battle of the unseeded players with Ecuador's Nicolas Lapentti, triumphing 6-2 3-6 6-3.

Fernando Gonzalez continued his winning run against James Blake to oust the 13th seed in straight sets.

The Chilean had won their previous six meetings and Blake could do nothing to end that sequence as the 17th seed secured a 7-5 6-1 victory.