Safina celebrated her 23rd birthday in Stuttgart on Monday
Dinara Safina cruised to victory over Sara Errani in her first match as world number one at the Stuttgart Grand Prix.
The Russian powered past the 37th-ranked Italian 6-0 6-1 in just 51 minutes to reach the second round at the first ever WTA indoor clay event.
Safina, who turned 23 on Monday, took the number one ranking for the first time in her career on 20 April.
Earlier, second seed Elena Dementieva struggled to a 6-4 3-6 6-3 win over Germany's Anna-Lena Groenefeld.
"It was a difficult match to play, with lots of ups and downs," said Dementieva. "I lost my concentration in the second set."
Denmark's Caroline Wozniacki
, the seventh seed, defeated Iveta Benesova of the Czech Republic 6-3 7-5.
Meanwhile, defending champion Jelena Jankovic
, who opens against Dominika Cibulkova on Wednesday, admits poor form has altered her expectations.
"I won't be thinking about defending the title here, it's more important for me to just get back to playing good tennis," said the Serb.