Italy went into the tie against an under-strength Russian side as heavy favorites, but very nearly found itself 1-0 down after an inspired performance by World No.136 Alexandra Panova in the first rubber.
In her first Fed Cup match, Panova made a mockery of her lowly ranking, matching Vinci stroke for stroke for over three hours on the Sardinian clay.
Appearing in her 26th match and third final, Vinci looked every bit the senior player early on, breaking for a 4-2 lead in the opening set. But Panova was in no mood to let her big opportunity slip by, reeling off five of the next six games to take the set.
And to the astonishment of the capacity crowd, there was no let up in the second as she raced into a 5-2 lead. With the finishing line in sight, though, she faltered, letting three match points slip by as Vinci hit back to force a decider.
Displaying admirable resolve, Panova did not fall away, hitting back to earn a third opportunity to serve for the match at 5-4. Once again, that final point proved to be the most difficult to win, as the Russian pushed a backhand wide on her fourth match point.
There would not be a fifth, and after three hours and 13 minutes Vinci finally closed out the match, 57 75 86, for her 50th win of the year.
"It was a tough match and there were a lot of ups and downs," Vinci said. "I was a little bit injured and at the end I had a little bit of cramps.
"My captain told me to try to play a lot of balls on the court. I think at the end she was a little bit tired and also it was the first time she played Fed Cup so there were probably a few nerves."
However, it was not all plain sailing for the World No.7, particularly in the second set where she fell 4-2 behind before turning it around.
"I was a bit down in the second set," Errani said. "I was very tired physically. Also the weather at night was a bit more heavy so it was not so easy for me.
"I can play much better of course. I am a little bit tired and there is a lot of tension so it is not easy to play in Fed Cup. Also when you are favorites like this it is not easy."
Errani can clinch victory for Italy in Sunday's first singles rubber. She is scheduled to take on Panova although Russia's captain Shamil Tarpischev would not rule out the possibility of fielding Alisa Kleybanova, who hold two wins over Errani.