Errani and Vinci are at 15 wins in a row and counting following their 63 62 triumph, which also made them 3-0 all-time versus Jurak and Marosi without having dropped a set. They also improved to 19-2 on the year, having reeled off titles at the Australian Open, Paris [Indoors] and Doha during their streak.
"Everything is going well this year," Vinci said. "We have won a lot of tournaments. We are No.1 in the world. We are happy off the court.
"Jurak and Marosi played well today, but we played better. We will see what happens the rest of this tournament, but we are definitely confident."
The competition will stiffen in the next round, as they play Hsieh Su-Wei and Peng Shuai, who have won four WTA titles together. The Taiwanese-Chinese pairing rallied from a 4-2 first set deficit and 3-0 second set deficit in scoring a 64 76(4) victory over Svetlana Kuznetsova and Flavia Pennetta. In their only previous clash with Errani and Vinci at January's Australian Open, they won the second set 6-0 against the eventual champions before falling in a tight three-setter.
"We played so well today," Hradecka said. "I'm very pleased about that, because we didn't have a great start to the year, especially at the Australian Open and in Memphis. So this is encouraging.
"Indian Wells is a very nice tournament with nice facilities. They do everything for the players. For me, it's like the fifth Grand Slam."
Also advancing were No.6 seeds Nuria Llagostera Vives and Zheng Jie. In a mild upset, Marina Erakovic and Heather Watson won four straight games from 4-2 down in the second set for a 63 64 defeat of No.7 seeds Raquel Kops-Jones and Abigail Spears. They also beat the Americans in last year's Stanford quarterfinals en route to one of their two WTA titles together.
Friday's doubles schedule will be highlighted by Lisa Raymond and Samantha Stosur's opener against Bethanie Mattek-Sands and Sania Mirza. Raymond has an event-record seven titles here, two of which came with Stosur. Mattek-Sands and Mirza are fresh off their second title of 2013 last week in Dubai.